PubMed Health⌕ Search

Biomedical subjects

A Firestone

Publications and source records attributed to A Firestone.

14 recordsLinked to original sources
PubMed2001

Ethanol inhibits spontaneous activity of central nucleus of the amygdala neurons but does not impair retention in the passive-avoidance task.

BACKGROUND: Behavioral studies using pharmacological manipulations that increase neuronal activity of the central nucleus of the amygdala (CeA) have implicated the CeA in enhancement of memory modulation. To date, however, there has been a dearth of studies investigating the effect of a drug that decreases CeA activity on memory modulation-a drug that inhibits the neuronal activity of the CeA might be expected to impair memory modulation. To determine whether ethanol inhibits CeA activity and, if so, whether decreased CeA activity is associated with impairment of memory modulation, this study investigated the effect of ethanol on spontaneous single-unit activity of CeA neurons and retention in the passive-avoidance task. METHODS: The effect of ethanol (0.35, 0.75, 1.5, 2.5 g/kg) was determined on spontaneously firing neurons in the CeA in urethane-anesthetized rats by use of standard in vivo single-unit electrophysiological recording techniques. Additionally, the effect of ethanol when administered immediately after training in a standard passive-avoidance task was determined on retention the following day. RESULTS: Ethanol profoundly inhibited spontaneous CeA firing rates in urethane-anesthetized rats at all doses tested. Maximal inhibition was related to dose. Each dose of ethanol significantly inhibited CeA activity within 15 min of administration; within 35 min of administration, 0.75 g/kg of ethanol inhibited CeA activity by 65.2%, and the highest dose (2.5 g/kg) produced nearly complete suppression of CeA activity (81.3%). Although ethanol markedly inhibited CeA activity, these same doses of ethanol failed to impair retention in the passive-avoidance task: 0.35, 0.75, 1.5, and 2.5 g/kg of ethanol, administered immediately after training, failed to alter latency to step-through the following day. CONCLUSIONS: These results show that ethanol profoundly inhibits spontaneous CeA activity and suggest that inhibition of the CeA is not sufficient to impair retention in the passive-avoidance task.

Amygdala↗
PubMed1995

In vivo diagnosis of fissure caries using a new electrical resistance monitor.

The aim of this investigation was to study the accuracy of a newly developed electrical resistance monitor in diagnosing occlusal fissure caries in vivo in teeth without cavitation. The electrical resistance was measured in vivo on human third molars without existing restorations and without any macroscopic carious cavitation. Data from 41 sites on 26 occlusal surfaces were obtained. After measurement, the teeth were extracted, histologically prepared, and serially sectioned perpendicular to the occlusal surface and examined for the presence of caries. Nineteen sites had no caries, 7 had enamel caries, and 15 sites showed dentinal caries, 4 of which deep dentinal caries. For the diagnosis of occlusal caries with the electrical resistance monitor, the specificity was 0.77, the sensitivity 0.93, and the accuracy 0.83. Likelihood ratios for four diagnostic levels (no caries, enamel caries, dentinal caries, and deep dentinal caries) were 0.09, 0, 3.47, and 4.16, respectively. Diagnosis of occlusal caries using conventional bite-wing radiographs showed a specificity of 0.77, a sensitivity of 0.62, and an accuracy of 0.71. The electrical resistance monitor was well suited to detect in vivo occlusal caries under clinically intact fissures. The rather high value (0.23) of false-positive ratings, however, might lead to a substantial number of sound teeth being restored unnecessarily. Substantial improvement of occlusal, caries diagnosis may be achieved by combining this method with others.

Adult↗
PubMed1979

Gingival blood circulation after experimental wounds in man.

Capillary blood circulation following experimental wounding was observed by fluorescein angiography. Contralateral punch wounds 1.5 mm in diameter were made in healthy mandibular labial attached gingiva of 31 volunteers. Areas of ischemia were clearly visible angiographically 6 hours after wounding and were significantly greater in area (P less than 0.05) and wider (P less than 0.01) for wounds in the long axis of mandibular incisors (N = 14) than those on the vertical midline of the gingival papillae (N = 17). The ischemic changes occurred exclusively cranial to the experimental wounds. By the third day the epithelium adjacent to the wound margin in the central part of the ischemic area had necrotized, thus extending the wound coronally. By the seventh day the axial wounds were significantly (P less than 0.001) larger than the papillary wounds. The data strongly suggest that the blood supply of mandibular labial attached gingiva is preferentially oriented in an apico-coronal direction and that the capacity for collateral circulation is dependent upon local differences in vascular structure. The findings are applicable to flap design in periodontal surgery.

Adult↗
PubMed1978

Hemolysis in vitro by sorbose, sorbitol and xylitol.

L-sorbose, xylitol and sorbitol solutions (56 mM) were not hemolytic when incubated with erythrocytes of 30 healthy volunteers, 14 thalassemic heterozygotes and in 30 horses, 30 cows and 30 Osborne-Mendel rats. Lysis of dog erythrocytes was most pronounced when incubated with L-sorbose but was also significant in xylitol and sorbitol solutions.

Animals↗