Biomedical subjects

U Wingren

Publications and source records attributed to U Wingren.

21 records · Page 2Linked to original sources

PubMed1981

The effect of polymyxin B and some mast-cell constituents on mucosal mast cells in the duodenum of the rat.

Mucosal mast cells in the rat duodenum show no morphological signs of exocytosis of granules and do not release histamine after treatment with polymyxin B in doses large enough to cause almost complete degranulation of connective-tissue mast cells of tongue, skin, and mesentery with concomitant release of approximately 60% of the tissue histamine. Administration of polymyxin B in gradually increasing doses over a period of 5 ds resulted in a statistically significant increase in mucosal mast cells and a comparable increase in duodenal histamine content, whereas the connective-tissue mast cells in the other tissues examined became fewer in number, the remaining cells showing profound morphological changes, and tissue histamine levels, were reduced to approximately 40% of the controls. A similar increase in mucosal mast cells has been observed after treatment with another mast-cell secretagogue, compound 48/80. This suggests that the increase in mucosal mast cells may be an indirect effect of these compounds, related to their activation of other mast cells and mediated by material(s) secreted by the connective-tissue mast cells. Possible mediators such as heparin, histamine, and 5-hydroxytryptamine injected for 5 ds in doses large enough to account for the amount released from the degranulated mast cells had no effect on the morphology or numbers of mast cells in any of the tissues examined.

Animals↗

PubMed1980

Histamine content of peritoneal and tissue mast cells of growing rats.

The histamine and 5-hydroxytryptamine (5-HT) content of mast cells was measured in rat peritoneal mast cells (isolated by density-gradient centrifugation or in crude peritoneal cell suspensions) and in some solid, mast-cell-rich tissues (tongue, skin, and duodenum). The duodenum contains large numbers of mast cells belonging to the specific type of mucosal mast cell. The peritoneal cavity, tongue, and skin contains the classical, mature connective-tissue-type of mast cell. The approximate amine content in mast cells of solid tissues was calculated by combining the biochemical assays with cell counting. The amine content was related to the age and body weight of the rats, studied during a period of rapid body growth (25-233 days). In the connective-tissue-mast cells both amines showed an increase that was strongly correlated to age and body weight. The increment of histamine was not as large as that of 5-HT. In peritoneal mast cells the histamine content per cell was doubled during the growth period studied, whereas there was a sixfold increase of 5-HT. The estimated 5-HT content per mast cell of tongue and skin also increased in relation to body weight. The histamine/5-HT quotients in these tissues were similar, and decreased with increasing age as did the same quotients for peritoneal cells. Parallel cell counts and histamine assays indicated that the mucosal mast cells contained much less histamine than the connective-tissue mast cells, and this findings was supported by histochemical observations. The observations did not suggest that histamine is stored else-where than in mast cells. In the mucosal mast cells, too, the histamine content appeared to increase as a function of age and body weight. Duodenal 5-HT, which is to a large extent contained in enterochromaffin cells, did not increase in relation to body growth.

Aging↗

PubMedDate not supplied

Effect of epidermal growth factor on cell proliferation in normal and wounded connective tissue.

Epidermal growth factor has been previously shown to stimulate connective tissue repair in the perforated rat mesentery. The mechanism by which epidermal growth factor accelerates closure of mesenteric perforations has not been established, but epidermal growth factor may stimulate mitosis, contraction, migration, or angiogenesis. In the present investigation, the effect of epidermal growth factor on connective tissue cell proliferation was studied during the initial phase of repair of mesenteric perforations and in unwounded mesentery. Laparotomies were performed on Sprague-Dawley rats, and standardized perforations were made with a scalpel in the center of the mesenteric "windows," leaving every second window as an internal control. Twice daily for 4 consecutive days, beginning on the day of surgery, the animals received by intraperitoneal injection either 10 microg of epidermal growth factor dissolved in phosphate-buffered saline solution or phosphate-buffered saline solution alone. Cell proliferation was measured by either mitotic index of fibroblasts and mesothelial cells or DNA content of individual fibroblast cell nuclei in the wound area or in unperforated control windows. Laparotomy alone was found to enhance proliferation during the early postoperative period, as shown by increased numbers of S + G2 fibroblasts and a greater mitotic index. Epidermal growth factor treatment increased the mitotic index in perforated windows on the third postoperative day, compared with controls treated with phosphate-buffered saline solution, but did not significantly increase either the number of S + G2 fibroblasts or the mitotic index in unwounded tissue. Also, the proliferative response after epidermal growth factor treatment was significantly higher in wounded tissue. This study shows that epidermal growth factor stimulates proliferation of connective tissue cells in wounded but not unwounded tissue, and such enhancement of fibroblast proliferation might be of importance in epidermal growth factor-stimulated connective tissue repair.

Journal Article↗