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Biomedical subjects

S Ishigaki

Publications and source records attributed to S Ishigaki.

At least 19 recordsLinked to original sources
PubMed2006

Occlusal interference during mastication can cause pathological tooth mobility.

BACKGROUND AND OBJECTIVE: Despite little evidence regarding the relationship between tooth mobility and nonworking contact, the evaluation of occlusion is performed mainly by the detection of premature and/or nonworking contacts during tapping movements and lateral excursion. The hypothesis of this study is that occlusal contact during mastication is potentially traumatic to periodontal tissue. It clarifies the relationship between chewing patterns and the status of periodontal tissue. MATERIAL AND METHODS: Subjects included 73 adults, 20-29 years of age (39 men and 34 women), with complete sets of teeth and no history of orthodontic treatment or periodontal disease. The closing chewing patterns of each subject were classified into three groups by the Masticatory Deviation Index, which depicts the deviation from the normal chewing patterns within 5 mm from the intercuspal position. Periotest was used to diagnose teeth mobility and the values were compared among the three groups. RESULTS: The present study indicates that the chewing movements which deviated from the normal chewing movements increased the mobility of specific types of teeth. CONCLUSION: The results of this study imply a relationship between chewing movements and tooth mobility and indicate that functional evaluation of occlusion is necessary for the examination of periodontal tissue. Occlusal evaluation with border and tapping movements might be insufficient, and functional occlusal evaluation during chewing movements can be clinically useful for using to evaluate periodontal tissue.

Adult↗
PubMed2003

Influence of abutment substrates on the colour of metal-free polymer crowns.

New-generation composite materials have excellent strength and wear resistance, and thus can be used to make metal-free crowns. However, composite materials are translucent, and so when using them to make metal-free crowns, it is necessary to take the effect of the abutments into consideration. In this study, five types of materials including three types of new-generation composite materials, a conventional composite material, and a ceramic material were used to examine the translucency (contrast ratio) of the materials and the effects of the colour of the abutments on the final appearance of metal-free crowns. It was found that the materials varied slightly from one-another in translucency and that it was possible to reproduce the desired colour when gold alloy was used for the background. However, it was difficult to produce an adequate colour match when silver-palladium alloy was used for the background. When a tooth colour material that was darker than the target colour was used for the abutment teeth, some materials could not reproduce the target colour satisfactorily.

Composite Resins↗
PubMed2002

Influence of abutment substrate and ceramic thickness on the colour of heat-pressed ceramic crowns.

All-ceramic crowns made of leucite-based heat-pressed ceramics are widely used to restore non-vital teeth in conjunction with various post and core materials. However, as some light passes through the ceramic, the colour of the abutment substrate can negatively affect the final aesthetic appearance of the all-ceramic crown. In this study, we made background specimens simulating gold-alloy cast posts and other simulating porcelain veneered cast posts, overlaid different thickness of heat-pressed ceramic on these background specimens, and measured the shifts in colour. We found that, when the background specimen was a gold alloy, the background colour had an effect on the apparent colour, unless the ceramic was more than 1.6 mm thick. When the background specimen was porcelain veneered, the background colour had no evident effect, even when the ceramic was not very thick. Therefore, when making a restoration using a leucite-based heat-pressed ceramic crown, it is advisable to use tooth-coloured materials such as a porcelain veneered cast post, if you will not be able to make the ceramic more than 1.6 mm thick.

Aluminum Oxide↗
PubMed2002

Fracture resistance of pressable glass-ceramic fixed partial dentures.

The aim of the present study was to evaluate the mechanical strength of the Empress2 system, which is based on the use of a high-strength glass--ceramic core of lithium disilicate, and the fracture resistance of fixed partial dentures fabricated with this material. To evaluate mechanical strength, four types of ceramic materials were tested for four-point flexural strength and diametral tensile strength: Empress2 core material, Empress2 layering porcelain, conventional Empress material and Dicor. Then, using Empress2, conventional Empress and Dicor, actual clinical type anterior fixed partial dentures were fabricated for fracture testing. The results showed that the Empress2 core material, at 329 MPa, has more than twice the flexural strength of conventional materials and at 271 MPa, more than four times the diametral tensile strength of conventional materials. Furthermore, fixed partial dentures fabricated with Empress2 had a fracture resistance of 1424 N. That is, they were more than twice as fracture resistant as fixed partial dentures made with conventional materials.

Ceramics↗
PubMed2001

A novel centrosomal ring-finger protein, dorfin, mediates ubiquitin ligase activity.

We cloned a novel gene, Dorfin (double ring-finger protein), from human spinal cord. The Dorfin mRNA transcript was 4.4 kb and expressed ubiquitously in many organs as well as in the central nervous system, including the spinal cord. Dorfin encoded 838 amino acid protein Dorfin, which contains two RING-finger motifs and an IBR (in between RING-fingers) motif at its N-terminus. Dorfin is a short-lived protein. Treatment with MG132, a potent proteasome inhibitor, resulted in the accumulation of ubiquitinated Dorfin and Dorfin-associated cellular proteins in cultured cells. Dorfin bound specifically with human ubiquitin-conjugating enzymes UbcH7 and UbcH8 through the RING-finger/IBR domain. Partial deletion of the RING-finger/IBR domain eliminated these interaction and ubiquitination activities. These results strongly suggest that Dorfin is a new member of RING-finger type ubiquitin ligase. Dorfin is localized in the centrosome and probably functions in the microtubule organizing centers.

Amino Acid Sequence↗
PubMed2000

Two novel genes, human neugrin and mouse m-neugrin, are upregulated with neuronal differentiation in neuroblastoma cells.

We herein report two new genes, human neugrin and mouse homologue m-neugrin, found by screening the cDNA library for the human spinal cord. The neugrin mRNA encodes 219 amino acids and its deduced amino acid sequence contains an NLS-like domain. No previously known motif is found in it. m-neugrin mRNA encodes 233 amino acids. Neugrin and m-Neugrin are 70% homologous in amino acid sequence. Northern analysis revealed that neugrin was strongly expressed in the heart, brain, and skeletal muscle, and m-neugrin in the liver, kidney, and brain. A transfection study indicated that these proteins are localized in the nucleus. Although the expression of neugrin was found to be ubiquitous in the nervous system, in situ hybridization showed that both neugrin and m-neugrin were expressed mainly in the neurons rather than the glial cells. Their expression was highly upregulated with the neurite outgrowth associated with neuronal differentiation in neuroblastoma cell lines. These results indicate that neugrin and m-neugrin are mainly expressed in neurons in the nervous system, and play an important role in the process of neuronal differentiation.

Amino Acid Sequence↗
PubMed2000

[Evaluation of a new method for antifungal drugs susceptibility testing to yeasts].

We compared the Etest with a broth microdilution method (FP panel), performed according to the National Committee for modified Clinical Laboratory Standards (NCCLS) document M27-P guidelines, for determining the MICs of 81 clinical isolates of yeasts (7 Candida albicans, 8 Candida glabrata, 10 Candida parapsilosis, 6 Pichia anomala, 10 Candida tropicalis, 4 Candida guilliermondii, 4 Candida krusei, 6 Trichosporon cutaneum, 5 Candida ciferrii, 3 Candida famata, 4 Candida norvegensis, 2 Rhodotorula rubra, 3 Candida lusitaniae, 2 Candida curvata, 1 Candida inconspicua, 1 Candida intermedia, 1 Candida colliculosa, 1 Cryptococcus spp, 1 Tricosporon capitatum, 1 Pichia ohmeri, 1 Saccharomyces cerevisiae). The Etest results for 6 ATCC standard strains correlated well with reference MICs except those of flucytosine (5-FC) for C. krusei, which tended to be 1 to 2 log2 dilution higher than the MIC range determined by NCCLS guidelines. However, the best agreement between the results for clinical isolates was seen with 5-FC (100% agreement [Within +/- 2 log2 dilutions] between the results of the two methods). There was a 91.4% agreement between the results of the two methods with amphotericin B (Etest MICs tended to be 1 to 2 log2 dilution lower than those of the FP panel). The Etest results with litraconazole for clinical isolates except C. tropicalis were similar to MICs of the FP panel (Etest for C. tropicalis showed 1 to 2 log2 dilution lower than FP panel). Also, the Etest results with fluconazole for clinical isolates except C. tropicalis were similar of 1 log2 dilution higher than MICs of the FP panel (Etest for C. tropicalis showed more than 2 log2 dilution lower than FP panel). These results showed a good level of overall agreement between the Etest method and the broth microdilution test (FP panel). Since the Etest is a less laborintensive and much simpler method, it appears to be a useful procedure for testing the susceptibility of yeasts to antifungal agents.

Antifungal Agents↗
PubMed2000

[Pure red cell aplasia induced by clomipramine hydrochloride in a patient with SLE].

A 48-year-old woman, who had been suffering from systemic lupus erythematosus (SLE), developed normochromic normocytic anemia after receiving clomipramine hydrochloride. Her reticulocyte count was low, and a bone marrow aspirate revealed erythroid hypoplasia without involvement of other cell lines. Thus a diagnosis of pure red cell aplasia (PRCA) was made. The anemia gradually resolved following withdrawal of the drug. Although several drugs are known to cause PRCA, this is the first time that clomipramine hydrochloride has been reported to have such an effect. The underlying SLE in this case suggested the possible immunological pathogenesis of drug-induced PRCA.

Antidepressive Agents, Tricyclic↗
PubMed1999

Significance of membrane type 1 matrix metalloproteinase expression in breast cancer.

Expression of matrix metalloproteinases (MMPs) plays an essential role in tumor metastasis and invasion through the degradation of extracellular matrix (ECM). MT1-MMP (membrane type 1 matrix metalloproteinase), a membrane-type MMP, is responsible for the activation of MMP2. In this study the significance of MT1-MMP expression in human breast tumors was investigated by immunocytochemical assay, and its correlation with clinicobiological features was analyzed. MT1-MMP expression was detected in tumor cells and/or stromal cells, and there was a strong correlation between the expressions of MT1-MMP in the two cell types. Out of 183 primary tumors, 103 (56.2%) showed positive staining of MT1-MMP in tumor cells. MT1-MMP expression showed no significant correlation with any of the clinicobiological parameters examined, including hormone receptor status and angiogenesis. In postoperative survival analysis, MT1-MMP expression itself was not a significant prognostic factor. However, in the particular subgroup with the accumulation of thymidine phosphorylase (TP)-positive stromal cells, which have been activated by various stimuli, such as cytokines and hypoxia, MT1-MMP expression had a significant prognostic value. These data suggested that MT1-MMP might function cooperatively with tumor-associated stromal cells for the progression of breast cancer.

Breast Neoplasms↗
PubMed1999

Use of PCR serum in diagnosing and monitoring cytomegalovirus reactivation in bone marrow transplant recipients.

We previously reported that the use of polymerase chain reaction (PCR) in detecting cytomegalovirus (CMV) DNA in serum (sPCR) enables the detection of CMV viremia, which has not been possible with other methods. In this study, the clinical usefulness of sPCR was investigated by comparison with the results of three other diagnostic methods, i.e., antigenemia assay (AG), shell vial culture test (shell vial), and complement-fixing (CF) antibody titer. The present study included 26 patients with hematological diseases who had undergone allogeneic bone marrow transplantation (BMT). A total of 347 samples were collected, and the results of the sPCR and AG methods were in agreement in 91.1% of the samples. When a subject was positive in both the sPCR and AG tests, and the other two tests (shell vial and CF) were also positive, CMV reactivation was surmised as definite. When only the result of the shell vial test or the CF test was positive, these results were taken as false-positives. The time at which the samples became positive in each of these four tests was 7.5 weeks post-BMT for sPCR, 7.0 weeks post-BMT for the AG test, 7.4 weeks post-BMT for the shell vial test, and 9.7 weeks post-BMT for the CF test. Thus, it was found that samples became positive at almost the same time for the sPCR, AG, and shell vial tests. Interstitial pneumonitis (IP) due to CMV developed in 3 subjects. These cases were positive in the sPCR, AG, and shell vial tests prior to the manifestation of symptoms of IP. The CF test did not become positive until after the onset of the disease. As the IP due to CMV was controlled with treatment, the sPCR and AG tests became negative. With the shell vial and CF tests, on the other hand, the test results continued to be positive even after the IP was cured. These findings demonstrate that the sPCR test method--like the AG test--yields few false-positive results. Therefore, the sPCR method is useful in early diagnosis of reactivation of CMV and for evaluation of the efficacy of therapy administered for IP. In addition, sPCR can be performed simultaneously on a large number of samples, and the evaluation of the test results is simple. We conclude that the sPCR test may be superior to the three other diagnostic methods for evaluation of serum samples from multiple institutions.

Adolescent↗
PubMed1998

Metalloproteinases and tissue inhibitors of metalloproteinases.

Because the proteolytic degradation of extracellular matrix is required for invasion and metastasis, it would appear that the important family of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) might be prognostic indicators of the invasive potential of a breast tumor. Nevertheless, there are few data demonstrating an independent prognostic value of any individual MMPs or TIMPs in primary breast cancer patients. It is possible, however, that the balance among levels of certain MMPs and their inhibitors will be more informative, since MMPs are clearly involved in paracrine tumor-stromal interactions and are associated with angiogenesis, which does appear to be prognostic.

Breast Neoplasms↗
PubMed1995

CMV viraemia demonstrated in the serum of a patient with cytomegalovirus pneumonia.

We attempted to demonstrate the expression of cytomegalovirus (CMV) particles in the serum of an acute lymphocytic leukaemia patient with CMV pneumonia. The serum sample was applied to an affinity column coupled with human monoclonal antibody C23 which recognizes the envelope glycoproteins of CMV virus and neutralizes the viral activity. The DNA obtained from each fraction was amplified by double polymerase chain reaction (PCR) and analysed by gel electrophoresis. Bands were clearly observed in the eluted fraction. These results strongly suggest that CMV particles exist in the sera of patients with CMV pneumonia.

Base Sequence↗
PubMed1995

[Effect of h-PTH on bone and bone marrow tissue in experimental osteopenia in rat].

We have evaluated changes in bone volume, bone marrow tissue, and the density of osteoclasts caused by intermittent administration of human parathyroid hormone (h-PTH) to experimental osteopenia induced in rat by ovariectomy (OVX) or by diabetes mellitus (use of streptozotocin: STZ). A bone and marrow histomorphometric study was performed on HE-stained and tartrate-resistant acid phosphatase-stained (TRAP-stain) tibial bone sections. Retired Wistar rats, 7-8 months old, were used. They were separated into the following nine groups; sham operated, base line control, vehicle administered, low or high dosage h-PTH administered OVX and STZ groups. 6.0 micrograms/kg/day of h-PTH (1-34) as a low dosage, and 60.0 micrograms/kg/day as a high dosage, was injected subcutaneously six times a week for 4 weeks from 9 weeks after ovariectomy or injection of streptozotocin. The bone volume decreased in both the OVX and STZ groups, while the fat tissue volume increased in the bone marrow in the OVX groups to compensate for this decrease, and the foamy marrow tissue volume increased in the STZ groups. The bone volume and the mean trabecular thickness in both the OVX and STZ groups increased by the intermittent administration of h-PTH, while the TRAP positive trabecular surface and the number of osteoclasts decreased. There was no significantly different bone changes between the low and high dosage groups. It is thought that the TRAP positive trabecular surface represented not only the active bone resorption surface but also the related contiguous uneroded surface.

Animals↗
PubMed1994

Diagnostic accuracy of TMJ vibration analysis for internal derangement and/or degenerative joint disease.

Lower joint arthrography and videofluoroscopy were used to diagnose 297 joints from temporomandibular disorders (TMD) patients. The surface vibrations of the temporomandibular joints (TMJs) were recorded by electrovibratography and a parameter set was derived through frequency analysis. Total vibration energies were used as the primary separating threshold for abnormal joints. The following conditions were statistically discriminated by multi-variate analyses: I) meniscal displacement with reduction; II) meniscal displacement with a partial disk reduction; III) meniscal displacement without reduction; and IV) degenerative joint disease and/or perforation of the disk. Using the total vibration energy as a threshold, the diagnostic sensitivity for the abnormal joints was 82%, while the diagnostic specificity for the joints with no evidence of internal derangement was 75%. Discriminant analysis for the above-mentioned four conditions revealed a diagnostic sensitivity of 79.0%, 85.7%, 77.1% and 76.3% for conditions I, II, III and IV, respectively. The diagnostic specificity was 76.2%, 79.9%, 59.0% and 77.9% for conditions I, II, III and IV, respectively. It was concluded that vibration analysis of the TMJ could be clinically useful as a screening examination for TMD patients.

Discriminant Analysis↗
PubMed1994

Effect of the location of chewing on facial and jaw muscles activity and the mandibular movement.

This paper evaluates the influence of the location of chewing on facial and jaw muscles' activity and mandibular movements. Ten subjects with complete dentition performed following chewing sequences; 1) right side chewing (unilateral location-unspecified chewing); 2) chewing on right molars; 3) chewing on right premolars; and 4) chewing on anterior teeth. Bilateral activities of upper lip, cheek, masseter (anterior, middle and posterior parts), and anterior bellies of digastrics were recorded by surface electromyography. Mandibular movements were simultaneously recorded by electrognathography. Chewing on anterior teeth showed smaller masseteric activity in posterior part, smaller envelope of motion, and lower velocity of both opening and closing than unilateral location-unspecified chewing and chewing on right molars. Chewing on premolars showed smaller envelope of motion than chewing on molars. No significant difference was found between unilateral location-unspecified chewing and chewing on premolars or molars.

Adult↗