[Change in the number of epidermal growth factor receptors of hepatocytes during liver regeneration in rats]. / Izmenenie kolichestva retseptorov épidermal'nogo faktora rosta gepatotsitov pri regeneratsii pecheni u krys.

The number of epidermal growth factor (EGF) receptors was determined for rat's hepatocytes under condition of their regeneratory proliferation, following a partial hepatectomy. In the normal hepatocytes two classes of EGF-receptors are distinguished, with high and low affinity, respectively. As early as 2 hours after the partial hepatectomy the total number of EGF-receptors sharply decreases, those with high affinity being not determined at all. The patterns of autophosphorylation of EGF-receptors with low affinity, examined in regenerating liver hepatocytes, remained the same as in the intact liver: their kinase activity was EGF-dependent, tyrosine residues of receptor molecules, with molecular mass equal to 150-170 kDa, underwent phosphorylation.

[Effect of the epidermal growth factor on 1,2-dimethylhydrazine-induced carcinogenesis in the rat intestinal mucosa]. / Vliianie épidermal'nogo faktora rosta na kantserogenez, indutsirovannyi 1,2-dimetilgidrazinom v slizistoi obolochke kishechnika krys.

The radioimmunological and radioreceptor methods have been used to show that sialadenectomy leads to the stable decrease of the epidermal growth factor (EGF) concentration in saliva and blood serum. The mean number of colon tumours per rat was significantly lower among the rats which had been sialadenectomized before injections of the carcinogen, than in the control. But a sharp stimulation of carcinogenesis in the duodenal mucosa was observed after sialadenectomy. The production of the alpha-transforming growth factor with the EGF-competing activity for the EGF-receptors was found in the chemically-induced rat colon tumours.

[Proliferation of the intestinal epithelium and of the regenerating liver with a deficiency of the epidermal growth factor]. / Proliferatsiia épiteliia kishechnika i regeneriruiushchei pecheni krys pri nedostatke épidermal'nogo faktora rosta.

To determine the role of the epidermal growth factor (EGF) in the regenerative stimulation of intestinal epithelium and hepatocyte proliferation after partial resection of these organs the labeling index of the intestine and liver in sialadenectomized rats was studied. EGF concentration in the saliva and serum was determined using radioimmunoassay. The decrease in EGF concentration after the removal of submandibular salivary glands was shown to slower hepatocytes entering the mitotic cycle and to inhibit the activity of enterocyte proliferation in the small intestine. The data show pronounced in vivo mitogenic effect of EGF on the liver and intestinal epithelium.

[Characteristics of the epidermal growth factor receptors in the epithelium of the gastrointestinal tract of rats and in intestinal tumors induced by 1,2-dimethylhydrazine]. / Kharakteristika retseptorov épidermal'nogo faktora rosta v épitelii zheludochno-kishechnogo trakta krys i v opukholiakh kishechnika, indutsirovannykh 1,2-dimetilgidrazinom.

Using the Scatchard analysis of 125J-EGF binding it was shown that plasma membranes of gastric and small intestinal epithelial cells contain approximately 20 times less EGF-receptors (EGF-R) than liver cells. Investigation of the phosphorylation activity of EGF-R-kinase was performed in vitro on plasma membranes from intestine, intestinal tumours and liver cells. The main protein phosphorylated at tyrosine in the tumours was p34 but the intensity of EGF-R autophosphorylation and its total protein-tyrosine kinase activity were reduced (as compared with small-intestinal and liver cell membranes). In the tumours of the colon induced by DMH an increased binding of 125J-EGF has been observed as compared with normal colonic enterocytes and increased number of EGF-R was clearly demonstrated. Phosphorylation of p34 in the intestinal membranes proceeds much more intensively than that of EGF-R.

[Rapid isolation of highly purified epidermal growth factor by reverse-phase liquid chromatography]. / Uskorennoe poluchenie vysokoochishchennogo épidermal'nogo faktora rosta s pomoshch'iu zhidkostnoi khromatografii v obrashchennoi faze.

The first step in the isolation of murine epidermal growth factor (EGF) from submaxillary glands was the trace enrichment of the acid-ethanol extract on Sep-pak C18 cartridges using the step elution with ethanol. The fraction eluted by 60% ethanol contained above 75% of EGF. The final purification of EGF was achieved by reverse-phase liquid chromatography on Novapak C18 column in the gradient of acetonitrile. A comparison of the effectiveness of gel filtration (on Bio-gel P-60 column) and trace enrichment (on Sep-pak C18 cartridges) of the appropriate fractions were analyzed by the reverse-phase high-pressure liquid chromatography, which had demonstrated that hydrophobic separation of EGF had a number of advantages. The homogeneous character of EGF was confirmed by the silver staining of gels after disc-electrophoresis and isoelectric focusing (pI 4.8). The pronounced mitogenic effect of EGF on the primary culture of the rat hepatocytes is described.