Surface electromyography, force and single motor-unit data for inhibitory reflex responses in human masseter at two levels of excitatory drive

The inhibitory reflex response evoked by mildly noxious lip stimulation was tested in up to 100 trials at two different levels of pre-stimulus excitation. To regulate that excitation, the subject voluntarily controlled the firing rate of one motor neurone at 10 Hz, and then at 15 Hz while the reflex was tested. When the frequency of the motor-unit action potential (MUAP) in the controlled unit increased or decreased, the frequency of other active units' MUAPs also changed in parallel: that is, the frequency of one MUAP was an index of whole muscle excitation. The inhibitory response in the surface electromyogram (EMG) was quantitated by rectifying and averaging the signal, and by measuring its depth and area. The best correlation between the responses evoked in single units and the response in the whole muscle EMG at the two levels of excitation was obtained when the area of inhibition in the surface record was normalized to the pre-stimulus EMG level. The inhibitory response to lip stimulation in the masseter EMG decreased when the level of pre-stimulus excitation in the muscle was increased. This was confirmed using the reflex response in the averaged force data. The findings suggest that controlling one motor unit's firing rate is a useful method for controlling the whole-muscle excitation in quantitative reflex studies.     

Effect of an acute maternal fluoride dose on fetal plasma fluoride levels and enamel fluoride uptake in guinea pigs

We conducted this study to measure maternal plasma, fetal plasma, and fetal enamel fluoride concentrations for four hours following an oral F dose to near-term pregnant guinea pigs. We placed female guinea pigs on de-ionized (Group I) or 3-ppm-F (Group II) drinking water prior to breeding and during gestation. On the 57th day of gestation, we administered a maternal dose of NaF solution (0.6 mg F/kg) by stomach tube. We collected samples of maternal plasma, fetal plasma, and fetal enamel at baseline, at 15 and 30 min, and at one, two, and four h after administration of the dose. We assayed samples for F using a modification of the micro-diffusion and ion-specific electrode method. Group I mean baseline F values were: maternal plasma, 0.016; fetal plasma, 0.002; and fetal enamel, 7.0 ppm. Group II mean values were: 0.055, 0.004, and 19.0 ppm. After the maternal fluoride dose, the mean maternal plasma [F] rose sharply for 30 to 60 min and declined to about 50% of peak values by four h. Fetal plasma [F] changed less in absolute values, but similarly to maternal changes relative to baseline. Fetal enamel mean [F] rose more in Group II than in Group I. Baseline F status had an important effect on F uptake in fetal enamel following an acute maternal fluoride dose.     

Oral findings in patients with autosomal dominant hypophosphatemic bone disease and X-linked hypophosphatemia: further evidence that they are different diseases

Oral examinations were performed on 5 patients with hypophosphatemic bone disease (HBD) (2 males and 3 females), 14 patients with X-linked hypophosphatemia (XLH), and 4 affected XLH relatives (6 males and 12 females). The control subjects were the unaffected siblings and parents of the patients and unrelated healthy, gender- and age-matched subjects. Serum phosphorus values were the same by disease type and gender in patients with HBD and XLH. They shared certain dental abnormalities, in particular pulpal necrosis and large pulp spaces. However, only patients with XLH had Class III malocclusions and mild enamel defects, and males with XLH had more severe occlusal and enamel defects than females with XLH. Different dental phenotypes are further evidence that XLH and HBD are different diseases. The dental abnormalities were not prevented by treatment, instituted early in life, which raised serum phosphorus to the near normal range.     

Expression of epithelial and nervous-system-related antigens on pleomorphic adenoma of the salivary glands--an analysis of 20 cases

The expression of cytokeratin (40-52 kD), carcinoembryonic antigen (CEA), vimentin, neuron-specific enolase (NSE), S-100 protein, glial fibrillary acidic protein (GFAP) were investigated in 20 cases of pleomorphic adenoma of the salivary glands and 10 cases of normal salivary glands, in order to analyze and correlate the antigens' expressions with the probably histogenetic mechanisms of the various histopathological differentiations in pleomorphic adenoma of the salivary glands and their probably original cells in normal salivary glands. Immunohistochemistry has provided some evidence for the relationship of the tumor cells to normal salivary glands: In the normal glands, the acinic cells exhibited cytokeratin, CEA and focal, predominantly nuclear S-100 protein staining. In both normal glands and pleomorphic adenomas, the duct-lining cells were immunoreactive for cytokeratin, CEA and had both cytoplasmic and nuclear S-100 positivity; The myoepithelial cells of the normal glands as well as the periduct cells, epithelial nests/cords, squamous metaplasia and the stellate/spindle/cartilaginous cells in the myxomatous-chondroid areas of the pleomorphic adenoma contain immunoreactive vimentin, NSE, S-100 proteins and GFAP, and lesser amounts cytokeratin (40-52 kD)/CEA. The varicosities of the terminal axon may lie directly on the basal membrane, or penetrate the basal membrane and lie in direct contact with the effector cells (duct-acinar-myoepithelial cells) of the salivary glands. The peripheral neurons and axons of the autonomic nervous system were identified by vimentin, NSE, S-100 proteins and GFAP. The combination of epithelial cytokeratin and nervous system-related vimentin, NSE, S-100 and GFAP immunostaining in myoepithelium of the normal glands and in all component elements (particularly the periduct cells) of pleomorphic adenoma reflects pleomorphic adenoma of the salivary glands is an epithelial tumor, the probably original cells or the probably histogenetic mechanisms of the various histopathological differentiations is correlated not only with "duct-acinar-myoepithelial cells" but also with the neuroectoderm in the normal salivary glands."     

Presence of periodontal data in patient records of general practitioners

It has been reported that little diagnostic information concerning periodontal conditions is entered in patient records of general practitioners, but actual rates for such chart entries are unknown. Records of regular patients, seen at least annually, were randomly selected from the offices of 36 general practitioners in two North Carolina counties. In each office 80 records were selected for audit. After adjustment, the final sample consisted of 2488 audited records. Entries noting the presence or absence of 14 diagnostic conditions were identified for the five previous years and for the patient's most recent examination. The presence of a periodontal diagnosis or periodontal treatment plan was noted. The number of radiographic sets exposed in the previous five years and the age of the most recent set were determined for complete series/panoramic films and for bitewings. Across practices, the most frequent notations (20.5% within the past five years) concerned the presence of probing depths and calculus. Gingival bleeding (13%) and plaque (12%) were noted less frequently. A periodontal diagnosis was recorded in only 16.3% of the records. Annualized rates for radiographic sets were 0.09 for complete series/panoramic films and 0.50 for bitewings. These data suggest that, except for radiographs, the majority of patient records do not contain sufficient diagnostic information to describe patients' periodontal health.     

Chondrosarcoma of the mandible. Report of case and a survey of 23 cases in the Japanese literature

A huge chondrosarcoma of the mandible (80 X 95 X 100 mm in size) with extension into the infratemporal fossa is described. The tumour was successfully treated by surgical removal and postoperative irradiation. A survey of the Japanese literature revealed 23 cases of chondrosarcoma with involvement of the mandible. The tumours occurred equally in males and females whose mean age was 38 years. The molar region was the site of predilection. The most common symptom was swelling and it was accompanied by pain in 7 cases and paraesthesia in 5 cases. Radiographically, the lesions were quite variable and with the exception of 3 cases in which information was not available, they consisted of a combination of irregular radiopacity and radiolucency in 9 cases, whereas the predominant feature was radiopacity in 6 cases and radiolucency in 4 cases. There was no radiographical abnormality in 2 cases. Root resorption of adjacent teeth was noted in 3 of 6 cases where information existed. Computed tomography was thought to be quite valuable in determining the nature and extent of the tumour. Although an elevation of serum alkaline phosphatase was observed in our case, results of laboratory tests were mostly of no diagnostic significance. Surgical removal was employed in 22 cases alone or in conjunction with irradiation and/or chemotherapy. Of 14 cases on whom information was available, local recurrence occurred in 6 cases in which radiotherapy was not given and distant metastasis in 2 of 10 cases on whom information was available. Of 20 patients on whom information was available on the postoperative course, 7 patients died 5 months to 6 years after the primary treatment.     

Mandibulofacial dysostosis. Case report

A case of mandibulofacial dysostosis (Treacher Collins syndrome) is presented. Clinical features and skull radiographs revealed typical anomalies associated with the syndrome. Cleft of the soft palate and unerupted multiple supernumerary teeth were present in this case. No haematological, biochemical or immunological abnormalities could be detected in the patient. Pedigree analysis showed an autosomal dominant mode of transmission of the disease. Chromosomal studies did not reveal any structural or numerical discrepancies.     

The effect of porcelain laminate veneers on gingival health and bacterial plaque characteristics

Abstract. The aim of this study was to evaluate the response of microbial plaque and gingival inflammation to the placement of porcelain laminate veneers on anterior teeth. 9 patients, 7 female and 2 male (mean age of 30 years), with a total of 35 veneers were examined. The volume of gingival crevicular fluid (GCF), level of neutral proteolytic enzyme activity, gingival index (GI), plaque index (PII) and plaque bacteria vitality were measured at baseline and after the placement of veneers. The volume of GCF increased after the placement of veneers ( p =0.03). No statistically significant differences were found in proteolytic enzyme activity or GI ( p >0.05). There were statistically significant reductions in PII ( p =0.000) and plaque bacteria vitality ( p =0.018). Further research is required to assess the long-term influence of porcelain laminate veneers on gingival health and microbial plaque characteristics.     

Effect of autonomic nerve stimulation on bleb formation in striated duct cells of the rat submandibular gland

Several previous investigations have shown that blebs form on the apical surface of the striated duct cells of the rat submandibular gland on feeding after starvation. In the present report the influence of autonomic nerve stimulation on bleb formation was studied by electron microscopy. Both parasympathetic and sympathetic stimulation were performed, using electric nerve stimulation. In addition, sympathetic nerve stimulation in combination with alpha- or beta-adrenergic blockers was used. Massive bleb formation took place in response to sympathetic nerve stimulation. This response was almost completely abolished by the administration of alpha- but not by beta-adrenergic blocker. Bleb formation was not seen after parasympathetic nerve stimulation.