The purpose of this study was to establish broadband ultrasonic attenuation (BUA: dB/MHz) as bone mineral density (BMD) norms for healthy young Japanese and to evaluate the standard values for an ultrasonic bone analyzer (Cuba Clinical, McCue Ultrasonics Ltd., Winchester, England), which facilitates BMD measurement without exposure to radiation. The subjects were 472 healthy young individuals with no endocrine or skeletal disorders, 197 males (mean age 16y 5m) and 275 females (mean age 15y 7m) aged from 5 to 29 years. BUA was measured at the left calcaneus. The subjects were divided into five age-stratified different age groups of five years intervals. The mean BUA values (dB/MHz) obtained were 40.6, 60.9, 78.0, 90.4 and 86.0 for males, and 41.9, 61.0, 73.4, 68.4 and 70.8 for females in the 5-9, 10-14, 15-19, 20-24 and 25-29 age groups, respectively. A significant positive correlation was observed between BUA and age in both males and females except in the male 25-29 age group and the female 20-24 and 25-29 age groups. A significantly different BUA between males and females was found in the 20-24 and 25-29 age groups (p<0.001). The BUA values obtained in this study may serve as BMD norms for children and young adults. It might be thought that measuring BUA from childhood through early adulthood made it possible to determine peak values and peak periods of BMD, providing useful information for assessment of growth and development.

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The purpose of this study was to examine the apical foramen of root apices extracted during apicotomies. A total of 25 teeth extracted from 25 patients admitted to the Department of Conservative Dentistry at Tokyo Dental College's Chiba Hospital were used for the study. All patients were between 22 to 56 years of age at the time of the study, and each of the 25 cases was determined clinically on radiographs to be chronic apical suppurative periodontitis. Microsurgery was performed on all cases, and the extracted root apices were then observed using SEM. The results demonstrated a wide opening, greater than 350μm as measured along the major axis, of the apical foramen in 80% of the cases. Various characteristics indicative of resorption were observed around the apical foramen. These features included those believed to have been caused by overinstrumentation during root canal treatment as well as irregularly shaped areas presumed to be apical lesions that had enlarged and eroded. We observed a high frequency of manifestations of cementum resorption surrounding the root apices of teeth with apical lesions. Furthermore, we concluded that in the majority of cases in the present study, due to the fact that the apical foramen exceeded normal opening dimensions as a result of overinstrumentation during root canal treatment or resorption around the root apex, prolongation of the lesions had occurred in response to direct contact of microbial infectious matter and tissues surrounding the root apex over a large area. The above finding suggested that, in cases in which the apical foramen is destroyed through overinstrumentation larger than #35 or in which the apical foramen opens up to dimensions greater than 350μm due to pathologic resorption, surgical intervention may be indicated. On the other hand, in 64% of the cases, an accessory canal was observed in the root apical lesion. Based on this observation, the presence of an accessory canal in the root apex may contribute to some degree to the prolongation of the lesion.

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The purposes of this study were to investigate the distribution of cytokeratins in the different tissue types of ameloblastoma and to discuss the histogenesis of this tumor. CK19 and CK8, which are markers for odontogenic epithelium, reacted positively to the constituting cells in all types of ameloblastoma. This suggests that all types of ameloblastoma derive from odontogenic epithelium. However, the desmoplastic type diminished the odontogenic characteristics because the basal cells are negative to CK19. Immunoreactions of five kinds of cytokeratin revealed similar results in plexiform, follicular, acanthomatous, and granular cell types. The plexiform type is probably the original type of ameloblastoma; the other types have the characteristics of squamous epithelium, and the follicular, acanthomatous, and granular cell types can develop due to the differentiation of cells of the plexiform type into squamous epithelium.

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The purpose of this study was to compare the physical imaging properties of three kinds of imaging plates (IPs) used with two photostimulable phosphor systems for dental radiography: HR-V, used with the Digora, BAS-SR, and ST-V, used with the DenOptix for intraoral radiography and panoramic radiography, respectively. Sensitivity to X-ray, gradient, modulation transfer function (MTF), noise power spectrum (NPS), noise-equivalent quanta (NEQ), and detective quantum efficiency (DQE) were compared. All imaging plates were read using the DenOptix scanner with inactive automatic range control (ARC). The scanning resolution was set at 300dpi. Decay of image information by room light was also compared at inactive and active ARC settings. BAS-SR showed the lowest sensitivity, the lowest gradient, the highest MTF, and the highest NPS. ST-V showed the highest sensitivity, the highest gradient, the lowest MTF, and the lowest NPS. HR-V was the second best for all imaging properties examined in this study. NEQ and DQE of BAS-SR were lowest, and those of ST-V were highest at low spatial frequencies. However, BAS-SR showed relatively constant NEQ and DQE while those of ST-V decreased remarkably at high spatial frequencies. NEQ and DQE of HR-V were the second best at low spatial frequencies and the best at high spatial frequencies. Therefore, we concluded that HR-V has the best imaging properties for dental radiography among three kinds of IPs evaluated in this study. However, the light decay speed of image information with HR-V was remarkably faster than with BAS-SR. To adopt HR-V for a system with which IPs are treated in an ordinary room, the light decay should be taken into account.

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In this study, we investigated the effects of vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide 1-38 (PACAP) on the voltagegated calcium currents in hamster submandibular ganglion neurons. VIP and PACAP inhibited the high threshold voltage-gated calcium current in a voltage-independent and a concentration-dependent manner via the G protein-mediated pathway. L-, N- and P/Q-type components of the total maximum voltage-gated calcium current accounted for 48.0±3.1% (n=4), 35.1±4.7% (n=4), and 13.5±2.3% (n=3) of the total peak amplitude, respectively. VIP at a concentration of 1μM inhibited the L-type calcium current by 33.2%±1.4% (n=4), the N-type current by 31.0±3.6%, and the P/Q-type current by 3.2±1.1% (n=3). PACAP at a concentration of 1μM inhibited the L-type current by 35.6±5.7%, the N-type current by 34.4±3.1% (n=4), and the P/Q-type current by 6.4±2.1% (n=2). However, VIP and PACAP did not inhibit the low threshold voltagegated (T-type) calcium current. The rank order of potency was PACAP>VIP. In experiments replacing GTP with GDP-β-S, the inhibitory effects of VIP and PACAP were prevented. In experiments of double-pulse protocol, depolarizing conditioning pulses could not relieve the inhibition of total high threshold voltage-gated calcium currents produced by VIP and PACAP. Therefore, the inhibition of the high threshold voltage-gated calcium channels produced by VIP and PACAP in hamster parasympathetic neurons differed in its mechanisms from that of N-type calcium channels in rat sympathetic neurons.

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Restriction Fragment Length Polymorphism (RFLP) related to cystatin gene (CST) family was detected in the Japanese population by using restriction enzyme Sac I. A polymorphic site, located at 0.9kb from the 3´ end of the CST2 gene, revealed a two allele polymorphism with band sizes of 3.5kb and 8.3kb by hybridization with probe including exon 2 of the CST1 gene. The gene frequencies in the Japanese population were 0.326 for 3.5 kb allele and 0.674 for 8.3kb allele (n=86). The phenotypes of the polymorphism showed no association with the previously reported electrophoretic cystatin SA protein phenotypes²²⁾.

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