Unique intronic variations of HLA-DQ beta gene in early-onset periodontitis

Human leukocyte antigen (HLA) class II beta chain plays an important role in the recognition of foreign antigens in immune reactions. Different forms of immune reaction may be concerned with initiation and progression of infectious diseases such as periodontitis. In this study we examined the frequency of HLA class II serotype and the variation of HLA class II beta gene in periodontitis patients. HLA serotypic frequencies in 70 Japanese patients with periodontitis and 26 individuals with periodontal health were examined. No HLA serotype specific to any type of periodontitis was observed. In order to detect differences among some HLA serotypes, restriction fragment length polymorphism (RFLP) analysis was undertaken with cDNA probes for HLA-DR beta and HLA-DQ beta genes in 20 subjects (15 patients and 5 healthy individuals). Atypical BamHI and EcoRI restriction sites were found in the HLA-DQ beta gene from 3 patients with early-onset periodontitis. In addition to these 20 subjects, an additional 80 subjects (40 patients and 40 healthy individuals) were screened for the atypical BamHI restriction site using the polymerase chain reaction method. It was detected in 7 patients with early-onset periodontitis, 1 patient with adult periodontitis, and 3 healthy subjects. No clinical differences except age were found between patients with this gene variation and other patients. Interestingly, all 3 healthy subjects with this gene variation were from subjects whose family members developed early-onset periodontitis with the gene variation. Atypical BamHI and EcoRI restriction sites and 41-nt repeated sequence were found in the intron before the third exon of HLA-DQB gene. These results suggest that these intronic gene variations may be useful as gene markers for a subpopulation of early-onset periodontitis and might affect immune reactions such as antigen recognition.

A new procedure of the tensile fatigue test for dental materials

A new tensile fatigue test using a stainless steel screw was introduced. A transparent PMMA rod was selected as the test material. A hole was drilled and tapped into the rod; a screw was put into the rod with dental cement or without cementation. Three types of cyclic loads were applied to the test piece; the number of times the load was applied when the initial crack was observed and when the final fracture occurred were recorded. Surface observation showed that actual fatigue fractures occurred in the test piece. The preferred applied load waveform was the cyclic haver-triangles load because of the small coefficient of variance. Fatigue strengths of test pieces with and without cementation were different. Cementation improved the fatigue properties, and the type of cement had an effect on the fatigue properties. Although the number of final fractures minus the number of initial cracks was the constant regardless of the type of cement used.

Interleukin-8 is a major neutrophil chemotactic factor derived from cultured human gingival fibroblasts stimulated with interleukin-1 beta or tumor necrosis factor alpha

Inflammatory mediators produced by cells in the gingiva have been implicated in the initiation and progression of periodontal disease, a common infectious disease. In this study, we examined the biological activity of neutrophil chemotactic factors and the kinetics of expression of interleukin-8 (IL-8) mRNA derived from normal gingival fibroblasts in response to inflammatory mediators in an in vitro model. Gingival fibroblasts stimulated by either recombinant human interleukin-1 beta or recombinant human tumor necrosis factor alpha produced neutrophil chemotactic factors after 4 h, whereas expression of cell-derived IL-8 mRNA was detected within 1 h after stimulation. Furthermore, in a neutralization assay, rabbit anti-recombinant human IL-8 antiserum inhibited neutrophil chemotactic activity to basal levels. These results provide evidence that gingival fibroblasts synthesize potent chemotactic factors such as IL-8 in the presence of the inflammatory mediators interleukin-1 beta and tumor necrosis factor alpha. The activity of these factors may contribute to neutrophil-mediated processes in the pathogenesis of periodontal disease.

Primary angiosarcoma of the right atrium detected by magnetic resonance imaging

A 20-year-old woman with a primary angiosarcoma of the right atrium is reported. The patient had a cardiorespiratory arrest due to cardiac tamponade with bloody pericardial effusion. Magnetic resonance imaging (MRI) revealed a tumor, which was corroborated by selective coronary angiography. Open-heart surgery was performed. The tumor relapsed however, and she died four months after operation. The tumor was undetectable by echocardiography, but MRI demonstrated a heterogeneous mass with focal areas of high- and low-signal intensity in the right atrium, suggesting that MRI may allow characterization of cardiac tumors.

[A fundamental study of 99mTc-ethyl cysteinate dimer (99mTc-ECD)]

In vitro fundamental studies of 99mTc-ethyl cysteinate dimer (99mTc-ECD), a newly developed radiopharmaceutical for cerebral perfusion scintigraphy, were performed, and were compared with those of 99mTc-HM-PAO, which has been widely applied to clinical use. 99mTc-HM-PAO should not only be injected soon after reconstitution, but also be avoided mixture with saline or drugs such as Diamox, because of its radiochemical purity decreases with the passage of time and the addition of saline and Diamox. On the other hand, the radiochemical purity of 99mTc-ECD reached a constant level of 94-96% at 30 to 180 min after reconstitution, and it remained stable against the addition of saline and Diamox. Therefore, it was suggested that 99mTc-ECD could be injected from an already saline-infused venous-line or mixed with Diamox. However, early injection after reconstitution should be avoided, because 99mTc-ECD did not become stable enough to maintain sufficient radiochemical purity until 30 min after reconstitution. The present studies are suggested that the red blood cell component is largely related to the metabolism of 99mTc-ECD in blood. Furthermore, from study of the metabolic rate using rabbit blood, it was suggested that a species difference existed in esterase activity in blood.

MRI of the gastroepiploic artery used as a bypass graft

The right gastroepiploic artery (RGEA) is recognized for its long-term patency as a coronary artery bypass graft, a property shared with the internal thoracic artery. The usefulness of MRI for noninvasive visualization and evaluation of the RGEA graft was assessed using a spine coil as the surface coil in 14 patients with graft patency verified by postoperative angiography. The graft was visualized by spin-echo imaging as a signal-void surrounded by lipomatous tissue with high-signal intensity in all 14 cases. Cine MRI was also performed in 13 of the 14 patients; in each case the graft was confirmed to contain blood flow of high-signal intensity.

Development of a new investment for high-frequency induction soldering

This study developed a new investment for induction soldering using high frequency induction heating. Ninety-five mass% magnesia clinker and 5 mass% dental stone were selected for the main constituents. The magnesia investment itself was scarcely affected by induction heating, so the addition of metal powders such as Fe, Ni, Co were investigated. Among these three powders, the addition of 10 mass% cobalt powder was most effective. This investment needed only 40 seconds of high frequency induction heating to go from room temperature to 900 degrees C without preheating. Thermal expansion of this investment in a vacuum atmosphere was 1.25% at 1000 degrees C. Dimensional changes during induction soldering were measured using German-silver and silver solder. When the new magnesia investment containing 10 mass% Co powder was used, the dimensional change was -0.2%. This contraction was less than when a magnesia investment without metal additives was used.

Oblique cine MRI for the evaluation of aortic regurgitation: comparison with cineangiography

The results of oblique cine magnetic resonance imaging (MRI) through a long axis slice of the left ventricle in 40 patients was compared with cineangiography in order to determine the usefulness of cine MR imaging for the evaluation of aortic regurgitation (AR). A diastolic dark low-intensity flow signal extending from the aortic valve into the left ventricle was seen in all 30 patients with AR, and in none of the 10 patients without AR. The length and area of the low-intensity signal due to the regurgitant flow were planimetered, and the ratio to the length and area of the left ventricle was calculated. The best correlation with angiography was with the ratio of the area of the low-intensity signal (ALIS) to the area of the left ventricle (ALV); it correctly classified the degree of regurgitation in 28 of the 30 patients (93.3%). The ALIS/ALV ratio was under 25% in all 11 patients with angiographic mild AR, 26-50% in 10 of the 11 patients with moderate AR, and over 51% in 7 of the 8 patients with severe AR. Thus the results point to a high degree of correlation between long axis oblique cine MRI and cineangiography in the identification of AR and in providing a semiquantitative estimation of its severity.

Humoral immune response to an antigen from Porphyromonas gingivalis 381 in periodontal disease

The humoral immune responses of patients with periodontitis were evaluated to characterize the host response to Porphyromonas gingivalis. A sonic extract of P. gingivalis 381 from whole cells was fractionated by gel chromatography and ion-exchange chromatography. The fractionated extracts were evaluated by Western blot (immunoblot) analyses with patient sera. A dominant antigen was identified from the sonic extract with an apparent molecular mass of 53 kDa. The 53-kDa protein antigen (Ag53) was purified by affinity chromatography by using a monoclonal antibody. Ag53 was detected on the vesicle surface of P. gingivalis 381 by immunoelectron microscopy by using the monoclonal antibody and was detected as a major protein in the outer membrane and in vesicles by Western blot analysis. Monoclonal antibody cross-reactivity to Ag53 in the sonic extracts of P. gingivalis ATCC 33277, P. gingivalis 1021, and Porphyromonas endodontalis ATCC 35406 was revealed. Seventy-seven patients with periodontitis were examined for their responses to Ag53. Serum immunoglobulin G (IgG) from 54 patients reacted strongly to Ag53; however, serum IgG from the remaining 23 patients did not exhibit detectable reactivity at all to Ag53, even though the patients had high serum IgG titers to the sonic extract. Ag53 is a new marker that represents an interesting aspect of the humoral immune response to P. gingivalis in patients with periodontitis.

Monoclonal antibody to a specific antigen from Wolinella recta ATCC 33238

Four monoclonal antibodies (m-Abs) to a specific antigen (150-kDa protein antigen) isolated from Wolinella recta ATCC 33238 by acid extraction were obtained. The four antibodies were all of the IgG1 subclass and exhibited equally high specificity for the antigen. A battery of 14 strains or oral bacteria were screened for cross-reactivity with each mAb by ELISA and Western blot analysis. Weak cross-reactivity to some strains was observed which differed depending upon the mAb. Immuno-electromicroscopic studies were performed with a mAb which revealed that the 150-kDa antigen was localized to the cell surface of W. recta ATCC 33238.

Isolation and partial characterization of a 39 kDa major outer membrane protein of Actinobacillus actinomycetemcomitans Y4

The outer membrane fractions of Actinobacillus actinomycetemcomitans, which were extracted from whole cells with cetyl trimethyl ammonium bromide and CaCl2, contained four major outer membrane proteins (MOMP) of 39, 37, 36 and 30 kDa. The 39 kDa MOMP of A. actinomycetemcomitans was sequentially purified by extraction with Zwittergent 3-14 detergent, anion-exchange chromatography and gel filtration chromatography. Analysis of amino acid composition and N-terminal amino acid sequence of 20 residues of purified 39 kDa MOMP was performed. Although some of the periodontitis patient sera reacted strongly with 39 kDa and 30 kDa MOMP in crude outer membrane fractions, purified 39 kDa MOMP showed decreased immunoreactivity with the human sera.

A family study of a mother and daughter with increased susceptibility to early-onset periodontitis: microbiological, immunological, host defensive, and genetic analyses

Microbiological, immunological, host-defensive, and genetic analyses were performed on a mother and daughter, both of whom had early-onset periodontitis (rapidly progressive periodontitis in the mother; localized juvenile periodontitis in the daughter). Microscopic examination revealed a greatly elevated percentage of rod-form bacteria in both subjects. Fusobacterium sp. and Porphyromonas gingivalis (formerly Bacteroides gingivalis) were the predominant microorganisms cultured. The humoral immune responses to F. nucleatum, P. gingivalis, and Actinobacillus actinomycetemcomitans were much higher in both subjects than those to any other periodontal bacteria examined. Functional and phenotypic analysis of the peripheral lymphocytes showed no significant abnormalities. However, investigation of neutrophil function showed that the mother had depressed neutrophil chemotaxis and superoxide production. The daughter had depression not only of chemotaxis and superoxide production, but also of neutrophil phagocytosis. Serological typing of HLA antigens revealed the same Class II HLA profile in both subjects. It was concluded that both subjects very probably had an identical condition and that these patients provided a unique model for improving our understanding of the host factors involved in periodontal disease.

[Casting accuracy and shrinkage of titanium castings made with zirconia investments]

To obtain inlay, crown and bridge types of titanium castings with sufficient size accuracy, zirconia investments with 10 mol % calcia were studied for their setting expansion, thermal expansion, total expansion, casting shrinkage compensation deficiency on fabrication method, particle size of zirconia, calcia and mixing liquid. Addition of calcia caused the change from contraction to expansion in setting and the additional thermal expansion at 900-1,200 degrees C. The choice of calcia and mixing liquid makes great influence on setting expansion, which is grouped into saturation type and delayed expansion type. By the use of the saturation type, total expansion could be controlled in the range of -2-(+)3%. Titanium castings of inlay, crown, bridge types with the values -2-(+)2% of casting shrinkage compensation deficiency could be successfully obtained. The casting shrinkage of titanium was estimated as 1.8-2%. The castings have the surface with a metallic brilliance as cast.

[Fatigue of dental zinc phosphate cement]

The fatigue characteristics of a zinc phosphate cement were examined. Using a split mould made of stainless steel, 12 mm x phi 6 mm column shape specimens were prepared. Fatigue tests were done by loading partially repeated pulsating diametrical tensile stress of 1-20 Hz, minimum stress was 0.2 MPa (2.0 kgf/cm2) and maximum stress was 3.5-5.4 MPa (36-55 kgf/cm2). During testing, the specimen was kept under distilled water. The existence of a fatigue was confirmed and there were marked signs of fatigue on the fracture surface. The relation between maximum stress and the number of cycles to fracture (S-N diagram) was obtained. Therefore the following equation and fatigue parameter (n) were deduced. logS + 0.0775.logN = 0.8931 n = 12.9 The fatigue characteristics depended on the frequency, that is, a time to fracture was shorter at the loading frequency of 20 Hz than that of 1 Hz.

Respiratory function and acid-base status in accidental hypothermia assessed by arterial blood gas analysis

To study the respiratory function and acid-base status in hypothermia, we retrospectively reviewed data of arterial blood gas analysis obtained from 63 patients with accidental hypothermia on admission. Twenty-nine showed acidemia and 16 showed alkalemia. The following results were obtained from 57 patients in whom blood gas analysis was performed in room air. PaCO2 was 46 mmHg or more in 2 and 34 mmHg or less in 46. Most of the patients exhibiting acidemia had metabolic acidosis except 2 with severe pneumonia or subdural hematoma. PaCO2 was low even in the patients with alkalemia. PaO2 was 60 mmHg or less in 8, of whom 7 had pneumonia, and 70 mmHg or more in most of the patients without pneumonia. We found that patients with accidental hypothermia generally showed a respiratory function proportionate to their decreased metabolism or hyperventilation, and most of the patients with acidemia exhibited metabolic acidosis.

[Effect of addition of calcia on the properties of zirconia investments]

The zirconia investments with calcia were studied of the compressive strength, setting expansion, thermal expansion, total expansion, thermogravitometry, differential thermal analysis on fabrication method, concentration, particle size of zirconia, calcia and mixing liquid. Addition of calcia caused the change from contraction to expansion in setting expansion. The optimum concentration of calcia was determined to be 10 mol% as judged from total expansion, strength and operability.

[Fracture toughness of human enamel irradiated by CO2 laser]

The fracture toughness (KIC) of human enamel irradiated by CO2 laser was examined by means of indentation microfracture method (IM method). The irradiation of laser from 1.5 watt (16 J/cm2) to 12.3 watt (133 J/cm2) was applied to enamel for 0.2 s, and the diamond cone of micro vickers hardness tester was pressed down by the 2.45 N (250 gf) under ordinary circumstances. At the irradiated spot, KIC was 0.24-0.86 MPam1/2 and Hv was 3.6 x 10(3)-4.3 x 10(3)MPa (370-440). At the non-irradiated spot, KIC was 0.83-0.9 MPam1/2 and Hv was 3.9 x 10(3)-4.3 x 10(3)MPa (400-440). A decreasing tendency of KIC was seen in all irradiated spots. The marked decrease of KIC started at the irradiation of 4.4 watt (47 J/cm2) and the rate of decrease was 22%, and 54% when exposed to the irradiation of 5.7 watt (61 J/cm2). The rate of the lowering of the KIC of 0.05 seconds' irradiation x 4 times was less than that of 0.2 s x 1 time, while cumulative total irradiation energy was equal. The measurement of KIC by the low force of 0.98 N (100 gf) seemed to be possible when KIC was 0.41 MPam1/2 and less.

Advantage of cine-MR imaging for the evaluation of valvular regurgitation

It is well known that the regurgitant blood flow of valvular disease shows a low intensity signal (LS) in cine-MR imaging (cMRI). To determine the significance of cMRI in evaluation of valvular regurgitation, 104 patients who had been assessed by cineangiography also underwent oblique cMRI for mitral regurgitation (MR) and aortic regurgitation (AR), and transverse cMRI for tricuspid regurgitation (TR). In evaluating the accuracy of diagnosis of valvular regurgitation on the basis of the presence of LS in the recipient chamber, sensitivity was found to be 93.5% for MR, 100% for AR and 85.7% for TR; specificity was 76.9% for MR and 100% for AR. The length and area of LS were planimetered in any view with the largest area, and its ratios to the length and area of the recipient chamber of view were calculated. Each index was significantly higher than the degree calculated by cineangiography. The best correlation with angiography was the ratio of the area of LS to the recipient chamber, and a semiquantitative classification by the index was coincident with angiographic severity in 38 of 43 (88.4%) patients undergoing MR, and in 28 of 30 (93.3%) patients undergoing AR. Thus, cMRI is a clinically useful noninvasive method in the identification and semiquantitative assessment of regurgitation severity.

[Setting characteristics of calcia-bonded investments by hydration]

Calcium oxide (CaO) slurry mixed with water hardens and expands by hydration. The authors used this setting characteristic as a binder of zirconia-refractory investments. If a mixed slurry was placed in air, unreacted residual calcia powders absorbed water and reverted to calcium hydroxide (Ca (OH)2). This resulted in a large setting expansion that continued for several days. A carbon dioxide (CO2) gas atmosphere controlled this expansion of calcia. When mixed slurry was placed in a carbon dioxide gas atmosphere, calcium carbonate (CaCO3) was formed and prevented the further hydration of unreacted calcium oxide. Thus setting expansion values were controlled. The combined expansion of setting and thermal expansion, in CaO-CO2-bonded zirconia investments, was about 1.5-2.5%. On the whole, calcium oxide is expected to be a good binder for high temperature dental casting refractory.

[Fracture toughness of human enamel]

The fracture toughness (KIC) of human enamel was examined by means of Indentation Microfracture Method (IM method). The IM method was a simple, efficient and economical means to obtain KIC of human enamel. Judging from the relationship between load and crack size, a median crack occurred in the range of 2.45-5.88 N, and KIC was hardly affected by the difference of surface roughness. KIC of a 58-year-old man's teeth was 0.61 MPam1/2 in 1 and 0.77 MPam1/2 in 7 and the difference was significant (P less than 0.01). KIC differed much from the direction of the indenter pressed to enamel rods and the KIC of the direction of enamel rods axis I was markedly higher than that of others. In the 58-year-old man's 1, KIC was 0.61 MPam1/2 in the direction of enamel rods axis V, 0.66 MPam1/2 in the direction of H and 0.84 MPam1/2 in the direction of I, and the difference was significant (P less than 0.01). The values for a 10-year-old man's permanent teeth was slightly higher but showed a similar inclination to the 58-yer-old man's teeth.

[Application of synthetic hydroxyapatite to periodontal therapy]

The purpose of the present study was to evaluate the effectiveness of granular hydroxyapatite as an alloplastic bone implant material in infrabony periodontal defects. Thirty-five infrabony defects in 28 subjects with marginal periodontitis were used. The patients were instructed in oral hygiene and received several sessions of scaling and root planing. Granular hydroxyapatite was implanted into test sites with infrabony defects following application of internally beveled full thickness flaps, root planing, and defect debridement. Pocket depth and attachment level were recorded before and 3 and 6 months after surgery. Gingival recession, mobility of the tooth, plaque index, and gingival index were also recorded before and 1 and 2 weeks, and 1, 3 and 6 months after surgery. Redness and swelling of the gingiva and increase in tooth mobility appeared transiently after surgery, however, they disappeared in a short time. A significant reduction of mean pocket depth of 3.4 mm and a significant increase in the mean attachment level of 2.5 mm were observed at 6 months after surgery. The mean gingival recession during the experimental period was only 0.9 mm. The amount of hydroxyapatite remaining implanted in the infrabony defect was 73% 6 months after surgery. The data and clinical impression suggest that hydroxyapatite has a potential as an alloplastic implant with clinically apparent acceptance by soft and hard tissue.