Search

An acromegaly-like rat model recently developed by exogenous administration of insulin-like growth factor I (IGF-I) was used to investigate morphological and histopathological tongue changes and clarify whether the changes were reversible. Human recombinant IGF-I (640 g/day) was continuously subcutaneously infused into ten-week-old male rats for four weeks (IGF-I group; n = 6). Control sham-operated animals were injected saline alone (control group; n = 6). Rats were sacrificed immediately on ending administration at the age of fourteen weeks. Another 12 rats (6 from each group) were housed for an additional four weeks after administration ended. Total IGF-I (human + rat) increased significantly during administration, returning to control levels afterwards. Tongue weights significantly increased with histopathological changes present (increases in the muscle-bundle width, spaces between muscle-bundles and epithelium thickness) in the IGF-I group compared to control rats. Tongue size returned to control levels after discontinuation of IGF-I administration. These findings suggest that the characteristic tongue enlargement was developed experimentally in our acromegaly-like rat model, and that such morphological and histopathological tongue changes are reversible on normalization of circulating IGF-I levels.

AbstractThe purpose of this study was to determine whether use of transmitted laser light would enable a better assessment of human pulpal vitality than back‐scattered light does (LDF: laser Doppler flowmetry). The experiments were carried out on ten upper central incisors in six subjects aged 23–28 years; five of the teeth were vital with no restoration, and five were non‐vital. For use with transmitted laser light, the fibers within the probe of a conventional LDF apparatus were used, one for transmitting light onto the buccal surface, the other for receiving it at the palatal surface of the same tooth. For LDF, the probe was fixed at the buccal surface. Blood flow was measured at three different locations on each experimental tooth: the incisal third, the center and the cervical third of the tooth crown. In non‐vital teeth, 1) output signals with transmitted laser light all registered zero, and no oscillation could be seen in recordings from any location on the tooth, but 2) LDF signals were above zero, there were regular oscillations related to heart rate, and passive increases in blood flow (corresponding to blood pressure increases) were recorded from both the center and the cervical third of the tooth, indicating that LDF registered blood flow of non‐pulpal origin. In vital teeth, LDF signals were significantly higher than in non‐vital teeth at each location on the tooth. At the central site on vital teeth, the output signals for transmitted laser light were about twice those seen with LDF, and passive blood flow changes corresponding to blood pressure increases were more clearly observed. These results indicated that transmitted laser light would be useful for the assessment of tooth pulp vitality both because the blood flow signals did not include flow of non‐pulpal origin, and because its output signals and response to blood flow changes were clear and could easily be monitored.

Retro - auricular galvanic stimulation in Romberg's posture elicits body sway which consists of an initial response (IR) and a deviation response (DR). Generally, anodal stimulation of the right side elicits IR to the left and DR to the right. We measured the deviation response (VDR) in various conditions in normal subjects. There was no significant difference between mean VDR in the standing posture weighted on the left foot (0.49 ° 0.17 cm) and on the right foot (0.39 ° 0.20 cm). Stimulation in the squatting posture also elicited IR to the left and DR to the right. Stimulation of the right side produced DR backward and to the right in the condition of the head facing to the right, and forward and to the right in the condition of the head facing to the left. The same body sway response as the after galvanic stimulation was also induced by non - galvanic manoeuvers like inclining the head or moving the finger. Anodal stimulation in the sitting posture elicited slight but apparent head inclination to the stimulated side. These results suggest that cervical muscles play an important role in the galvanic body sway test (GBST), viz. IR and DR seemed to be secondarily produced by changes in the muscular tension of the neck.