Effects of nicotine on the strength of attachment of gingival fibroblasts to glass and non-diseased human root surfaces.

BACKGROUND: The aim of this study was to evaluate the effect of nicotine on the strength of attachment of human gingival fibroblast cells to glass and non-diseased human root surfaces. METHODS: Human gingival fibroblast cells (HGF) were trypsinized, suspended in RPMI 1640 medium, and incubated with autoclaved human root and glass sections and nicotine (NIC) concentrations of 0 (control), 25, 50, and 100 ng/ml for 1 week. HGF attached and grew on glass and root surfaces for 4 weeks at all NIC concentrations. HGF cultures were subjected to a rotary shaker machine for 30 minutes to test the strength of attachment of these cells at 100, 150, and 200 rpm. The root and glass sections were examined at 48 hours by light microscopy. RESULTS: Control groups exhibited a monolayer of long, spindle-shaped fibroblasts with a parallel alignment and minimal overlapping. With a concentration of NIC of 50 or 100 ng/ml as well as with increasing "speeds," the number of cells attached to these surfaces decreased dramatically. When 200 rpm was used for both groups at all NIC concentrations, very few HGF remained attached to these surfaces. CONCLUSIONS: This study showed that the nature of cell attachment to either glass or root surfaces is altered by nicotine, and marked detachment was noted when nicotine exposure was coupled with vigorous agitation at different rpm. Marked detachment noted in all specimens at 200 rpm indicates that this speed is excessive for use in subsequent experimentation.

Histological changes in the skin of Rana pipiens produced by either KCl loading or fasting.

The present study was performed to determine if either potassium loading or fasting results in histological changes in the skin. Rana pipiens were loaded with KCl and skin biopsies obtained (Group I). These biopsies were compared with biopsies from NaCl loaded frogs (Group II). In blind studies of microscopic sections, 13 of 17 biopsies of a mixture of I and II were correctly diagnosed by one observer and similarly, 14 of 17 of Group I and II were correctly diagnosed by a second observer (P = 0.0245 and 0.0063, respectively). The characteristics used to distinguish skins from KCl treated frogs versus controls treatment included: (i) an abundance of large euchromatin cells on or near the surface; (ii) changes in the basal cell layer with elongation and rotation of the nuclei; (iii) lighter cells in the spinosal layers; and (iv) sometimes the skin became thicker. The water-soluble nondialyzable material of the frog skin was extracted, and we found that it increased by 4.4 times following KCl loading (P < 0.05). However, the protein fraction was not increased by loading the frog for 3 days with NaHCO3. We conclude that potassium loading results in characteristic histological changes in the skin and that this is probably related to the ability of the skin to excrete potassium. In addition, a comparison of biopsies of skin from fed frogs with samples from frogs fasted for 40 to 49 days showed a change in the thickness of the skin. Skins of fed frogs averaged 57.0 +/- 1.4 mu thick compared with fasted, 39.9 +/- 2.7 mu (P < 0.001).