Patients after ablative surgery for malignant tumors require computed tomography (CT) examination of a wide area on the head and neck to follow-up for recurrence and lymph metastasis. The aim of this study was to determine a more effective method for the infusion of the contrast medium into post-operative patients undergoing conventional CT, based on the relationship between the method of administering the contrast medium and the contrast-enhancing effect in the internal jugular vein. First eleven images were selected from the existing contrast-enhanced and plain CT images in a manner such that the CT values of the internal jugular vein were distributed evenly in a range of 50-180. Seven experienced observers evaluated the contrast-enhancing effect of each image set at a window value of 40 and window widths of 120, 200, and 280. Secondly, the CT values of the right internal jugular vein were measured in a total of 10 CT images from the thyroid to maxillary sinus level from each of 60 post-operative patients. The injection needles and contrast-enhancing techniques used in the 60 patients were drip infusion using an 18G injection needle in 20, drip infusion using a 21G injection needle with bolus intravenous injection immediately before scanning in 20, and drip infusion using a 23G injection needle with bolus intravenous injection immediately before scanning in 20. A CT value of 100 or above, preferably 120 or above, in the internal jugular vein was needed for the contrast-enhancing effect of a CT image to be judged as clinically significant. Our results found that, when a conventional CT was used in patients after surgery for malignant tumors, drip infusion using a 21G or 23G injection needle should be combined with bolus injections immediately before the beginning of scanning, and at the glottis or submandibular gland level during the scanning. A sufficient contrast-enhancing effect can also be obtained by drip infusion using an 18G injection needle without bolus injection.

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The relationship between the detection of Porphyromonas gingivalis, Bacteroides forsythus and Treponema denticola in subgingival plaque samples of periodontal pockets and periodontal status was evaluated using the polymerase chain reaction (PCR). A total of 165 sites in 60 periodontitis patients were examined, and the relationships between the detection of each of the three bacterial species and the pocket depth and bleeding on probing (BOP) were analyzed. The detection ratios of P. gingivalis, B. forsythus, and T. denticola in samples from adult periodontitis lesions were 75.5%, 69.8%, and 72.6%, respectively. It was found that all sites where all three microorganisms were detected were BOP positive and had greater pocket depths than those where only one or two species were found. The detection rate of B. forsythus and T. denticola decreased with age in the sites in which PD was less than 4 mm. The present study indicates that detection of a mixed infection by P. gingivalis, B. forsythus, and T. denticola strongly correlated with adult periodontitis.

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Histological changes in the masseter muscle were observed over time in mdx mice, a muscular dystrophy model. It was found that marked necrosis occurs about the time of weaning at around 4 weeks of age; then the tissue actively regenerates at 8 weeks and stabilizes as regenerated muscle with centronuclei at 15 weeks old. This study examined the centronucleus in regenerated muscle. The process from necrosis to regeneration in muscle fibers occurs a little later in the masseter muscle than in other limbic muscles. Regenerated muscles observed around 15 weeks after birth showed a moth-eaten appearance. Transmission Erectron Microscope (TEM) observation of transverse sections of muscle fibers revealed that myofibrils surrounded lost regions in the area showing a moth-eaten appearance. Thus, some defensive mechanism may affect the ability of muscle fibers to maintain a function close to normal in mdx mice even though the muscle fibers develop muscular dystrophy. The function of the masseter muscle drastically changes from sucking to mastication behavior at around 4 weeks, and this was considered to influence the morphological changes in the muscle tissue. The moth-eaten appearance seen at 15 weeks may represent an appropriate myofibril reconstruction preventing invasion of the lost regions.

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The purpose of this study was to investigate the adsorption of [³H]-thymidine labeled oral microorganisms to porous type calcium carbonate (PCC) beads in a buffer containing human parotid saliva and to PCC combined chewing gum sheets. Adsorption rates of Streptococcus sobrinus B13 and 6715, Streptococcus mutans MT8148R and Actinomyces naeslundii T14V with PCC were significantly higher than those with calcium carbonate (CC) beads (p<0.01). Adsorption rates of S. sobrinus, S. mutans and A. naeslundii with PCC combined chewing gum were significantly higher than those with CC combined chewing gum (p<0.01). The present results suggested that the chewing gum containing PCC may be able to exclude oral bacteria, including cariogenic and periodontopathic bacteria, for prevention of dental caries and periodontal disease.

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This survey was conducted to clarify which dental treatments in children are regarded as difficult by general dentistry practitioners. The subjects were 615 children who first visited Tokyo Dental College Chiba Hospital from January 1995 to August 1999 with reference letters. There were 615 children in the study; 571 (92.8%) came from Chiba City where our hospital is located and the 11 regions surrounding Chiba City. The prime reasons for referral in the order of frequency were treatments of dental caries, malalignment/malocclusion, traumatized teeth, supernumerary teeth, retarded eruption/ impacted teeth, abnormal direction of erupted teeth, congenitally missing teeth, prolonged retention of deciduous teeth, and abnormal frenulum. Patients with dental caries or traumatized teeth in the deciduous dentition period and those with malalignment/malocclusion, supernumerary teeth, or retarded eruption/impacted teeth in the mixed dentition period were often referred to medical organizations specializing in pediatric dentistry because of the difficulties in controlling the patients' behavior and in providing adequate treatment. The information about pediatric dental treatments considered difficult by general dentists revealed by this survey appears to be useful and needs to be incorporated in the programs for clinical training of undergraduate students and education of postgraduate students.

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We compared the effects of LPSs from P.gingivalis and P.heparinolytica on the induction of tumor necrosis factor-α (TNF-α) production by murine peritoneal macrophages. The lipopolysaccharide (LPS) preparation from P.gingivalis showed a typical ladder pattern in SDS-PAGE, whereas that from P.heparinolytica formed several stained bands without a ladder pattern. When the macrophages from C3H/HeJ mice were incubated with P.gingivalis LPS, the level of TNF-α released in the culture supernatants was significantly higher than that with P.heparinolytica. All tested reagents except genistein strongly inhibited the production of TNF-α by the macrophages after induction by either LPS. These results suggested the following possibilities, i) the induction level of TNF-α by P.heparinolytica is similar to that of Salmonella minnesota, ii) tyrosine phosphorylation is not the only pathway for the TNF-α production induced by these LPSs, iii) different regulatory mechanisms are involved in TNF-α production in P.gingivalis LPS stimulated and P.heparinolytica LPS stimulated cells.

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