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Biomedical subjects

S Masumi

Publications and source records attributed to S Masumi.

At least 19 recordsLinked to original sources
PubMed2005

Effect of light intensity on linear shrinkage of photo-activated composite resins during setting.

The purpose of this investigation was to examine the effects of light intensity on linear shrinkage of photo-activated composite resins during setting. The materials used were four commercially available photo-activated composite resins. Three light-irradiation instruments were selected and prepared so as to obtain four light intensities (200, 480, 800 and 1600 mW cm(-2)). The linear shrinkage during setting was examined 10 min after light irradiation using a trial balance plastometer, and the specimen thickness was 2.0 mm for all materials. The depth of cure was examined according to the test method described in the International Organization for Standardization (ISO/FDIS 4049: 2000(E)). In measuring the linear shrinkage 60 s from the start of light irradiation for 10 s, there was a significant correlation (r = 0.89-0.94) between the amount of linear shrinkage and the light intensity: an increase in light intensity produced a greater linear shrinkage. Furthermore, there was a significant correlation (r = 0.92-1.0) between the linear shrinkage and the irradiation time: an increase in irradiation time resulted in a greater linear shrinkage. Values of the depth of cure ranged from 1.69 to 3.75 mm.

Composite Resins↗
PubMed2005

Microbicidal efficacy of ozonated water against Candida albicans adhering to acrylic denture plates.

BACKGROUND/AIMS: Ozone is known to act as a strong antimicrobial agent against bacteria, fungi, and viruses. We examined the effect of ozonated water on Candida albicans on acrylic denture plate. METHODS: The heat-cured acrylic resins were cultured with C. albicans. After treatment of flowing ozonated water, the number of attached C. albicans was counted. In some experiments, the test samples were treated with ozonated water in combination with ultrasonication. RESULTS: After exposure to flowing ozonated water (2 or 4 mg/l) for 1 min, viable C. albicans cells were nearly nonexistent. The combination of ozonated water and ultrasonication had a strong effect on the viability of C. albicans adhering to the acrylic resin plates. There were no significant differences in antimicrobial activity against C. albicans between plates immersed in ozonated water with ultrasonication and those treated with commercially available denture cleaners. In addition, electron microscopic analysis revealed that small amounts of C. albicans remained on the plate after exposure to flowing ozonated water or immersion in ozonated water with ultrasonication. CONCLUSION: Our results suggest that application of ozonated water may be useful in reducing the number of C. albicans on denture plates.

Acrylic Resins↗
PubMed2004

Biomechanical properties of heat-treated bone grafts.

INTRODUCTION: A possible critical complication associated with banking bone is human immunodeficiency virus (HIV) infection. Recently, since the report of HIV infection in bone allografts from an HIV-seronegative donor, a more reliable method of sterilization for preserved bone graft has become necessary. Heat treatment of banking bone is one of the simple sterilization methods. This method is especially safe and practical for the prevention of HIV infection. MATERIALS AND METHODS: We previously reported a biological study on heat-treated bone graft. In that study, we showed that revascularization and new bone formation of bone graft after heat treatment at 60 degrees C was nearly the same as that of non-heat-treated bone graft, while at 100 degrees C, revascularization and new bone formation showed a significant delay. This time, we examined the change of mechanical strength of heat-treated bone grafts after transplantation in an experiment. To eliminate the problem of antigenicity of grafted bone, we used autografts, not allografts. Two types of heat-treated autografts were employed: heat-treated at 60 degrees C for 30 min and heat-treated at 100 degrees C for 5 min; as a control, fresh autografts were replaced in the left femur of rabbits. A strength test was performed for both the transplanted bone and the untreated intact right femur with time after transplantation. The strength test consisted of a compression test and torsional test, and the strength was compared between transplanted bone and the untreated intact right femur. RESULTS: In the compression test, the grafts heat-treated at 60 degrees C showed a strength ratio before transplantation of 97.3%. The strength ratio decreased to 63.5% at 18 weeks after transplantation. Then the strength ratio increased and recovered to 94.5% at 48 weeks after transplantation. However, the grafts heat-treated at 100 degrees C showed unsatisfactory mechanical strength, at 48 weeks the strength ratio was 60.1%, which was significantly lower compared with controls. In the torsional test, the grafts heat-treated at 60 degrees C showed almost the same strength observed in the compression test. However, the grafts heat-treated at 100 degrees C showed unsatisfactory mechanical strength: at 48 weeks, the strength ratio was 57.3%. CONCLUSION: Therefore, heat treatment at 60 degrees C is a useful sterilization method, not only in biological but also mechanical terms.

Animals↗
PubMed2002

Virtual endoscopic view of salivary gland ducts using MR sialography data from three dimension fast asymmetric spin-echo (3D-FASE) sequences: a preliminary study.

OBJECTIVES: We performed magnetic resonance (MR) sialography of parotid gland and/or submandibular gland ducts using three-dimensional fast asymmetric spin-echo (3D-FASE) sequencing. The objective was to make three-dimensional (3D) reconstruction images and virtual endoscopic views of the parotid gland ducts using MR sialography data sets of 3D-FASE sequences. METHODS: We reviewed the MR sialography data sets with 3D-FASE sequencing of 10 control volunteers and six patients. Three-dimensional reconstruction images and virtual endoscopic views of the parotid gland and/or submandibular gland ducts were generated with maximum intensity projection (MIP), shaded surface display (SSD), and volume rendering techniques (VRT). RESULTS: The main parotid gland and/or submandibular gland ducts, large branches within the glands, and small branches were fairly well defined in a very short acquisition time on MR sialographic images with 3D-FASE sequencing in nine of the 10 healthy volunteers. The 3D-reconstruction images of the parotid gland ducts and/or submandibular gland ducts showed the entire length of the branch paths and complete images from all angles, and the virtual endoscopic views showed the endoluminal tracts of the main ducts and the large branches in nine. In the patient with Sjogren's syndrome, chronic sialoadenitis, and salivary calculi in the Wharton ducts, the MR sialographic images showed diffuse areas of punctate high signal intensity, dilatation of Stensen's duct, or stones of Wharton's duct, respectively. Furthermore, the 3D-reconstruction images of the salivary gland ducts showed the stenoses and stones in the branch paths and complete images from all angles, and the virtual endoscopic views showed the stenoses and stones in the endoluminal tracts of the main and large branches. CONCLUSIONS: Our initial experience showed that virtual MR endoscopy could be performed to observe the endoluminal tracts of parotid and submandibular glands. The clinical use of the virtual MR endoscopy for salivary gland ducts has not been established yet. Future applications of the 3D-reconstruction images and virtual endoscopic views using MR sialography data sets of 3D-FASE sequences are very attractive and further expansion of this field is expected.

Adolescent↗
PubMed2002

Utility of frequency-selective fat saturation T2-weighted MR images for the detection of joint effusion in the temporomandibular joint.

OBJECTIVES: To evaluate joint effusion in the temporomandibular joint (TMJ) using frequency-selective fat saturation (FS) T2-weighted images and assess this technique. To investigate whether bone marrow abnormalities and magnetic resonance imaging (MRI) findings of internal derangement may be linked to joint effusion in the TMJ in patients with pain. METHODS: TMJ effusion was sought on FS T2-weighted images and conventional T2-weighted images in 400 joints from 200 patients with TMJ-related pain. Self-reported pain records were obtained from patients immediately before MRI and images assessed by the amount of TMJ fluid graded bilaterally using reference films by two radiologists. Other parameters recorded included disk displacement categories and condyle marrow abnormalities. The association between the recorded parameters and TMJ effusion judged by FS-sequences or conventional sequences was analysed using chi-square and Kappa tests. RESULTS: The detection rate of TMJ effusion by FS-sequences was significantly greater than by conventional methods, and the results showed a significant relationship between MRI interpretation of TMJ effusion using FS-sequences or conventional methods and the presence of pain. The correlation between TMJ effusion on FS-sequences and pain was significantly stronger than the conventional method. Kappa test indicated good agreement between pain and MRI TMJ effusion by FS-sequences (kappa = 0.66), but not by conventional sequences (kappa = 0.56). The other parameters showed a similar trend for TMJ-related pain. CONCLUSIONS: FS T2-weighted imaging is useful for detection of TMJ effusion, without known causes and confirms the importance of TMJ effusion as an indicator in patients with TMJ-related pain, bone abnormalities, and disk displacement.

Adipose Tissue↗
PubMed2002

The value of maximum jaw motion measurements for distinguishing between common temporomandibular disorder subgroups.

OBJECTIVE: The purpose of this study was to determine if mandibular motion measurements could be used to distinguish between common temporomandibular disorder (TMD) subgroups that were established on the basis of only clinical signs and symptoms. STUDY DESIGN: Patients were 41 consecutive TMD clinic patients (31 women and 10 men). These patients were divided into 6 typical TMD subgroups. The subgroups were patients with (1) arthromyalgia, (2) arthromyalgia with disk condyle incoordination, (3) disk condyle incoordination only, (4) osteoarthritis, (5) suspected disk displacement without reduction, or (6) other diagnoses. RESULTS: There were no subjects in the other-diagnosis subgroup and only 1 subject with suspected disk displacement without reduction who was dropped without further consideration. The data for mean age showed that the osteoarthritis subgroup (n = 12) was statistically older (17 years) than the disk-condyle-incoordination-only subgroup (n = 11). The mean age of the other 2 groups, arthromyalgia (n = 11) and arthromyalgia with disk condyle incoordination (n = 6), was between the osteoarthritis and the disk-condyle-incoordination-only subgroups. For the 4 TMD subgroups whose data were analyzed, the mean differences between similar jaw opening measurements ranged from 6 to 8 mm with a standard deviation of approximately 8 to 10 mm. The mean left lateral motions were 0.5 to 1.3 mm larger than observed on the right. The widest mean jaw opening (56 mm) occurred in the disk-condyle-incoordination-only group. These differences were not found to be statistically significant. CONCLUSION: Analysis of opening, lateral and protrusive jaw motion data showed these measurements could not reliably differentiate between patients with osteoarthritis, arthromyalgia, arthromyalgia with disk condyle incoordination and disk condyle incoordination only.

Adult↗
PubMed1999

Changes in hepatic nitrogen metabolism in isolated perfused liver during the development of thioacetamide-induced cirrhosis in rats.

Changes in hepatic nitrogen metabolism in isolated perfused liver were studied during the induction of experimental cirrhosis by thioacetamide in female Sprague-Dawley rats. Cirrhosis of the micronodular type developed during 12-week administration of thioacetamide. Despite an increase in food consumption for 4 weeks after the end of administration, the physiological changes characteristic of cirrhosis were maintained. The rate of urea excretion per unit liver weight was significantly decreased compared with pair-fed control rats both during and after thioacetamide treatment. During 4 weeks of thioacetamide treatment, the rate of urea production in perfused liver from a combination of 0.25 mM NH4Cl and 1 mM glutamine decreased slightly, without a decrease in the maximum rate of urea production from 10 mM NH4Cl. In cirrhotic rats, the rate of urea production in perfused liver from NH4Cl and/or glutamine decreased, with a decrease in the maximum rate of urea production. The Km of ureagenesis for NH3 was unchanged in cirrhotic livers. During 4 weeks of thioacetamide treatment, glutamate dehydrogenase activity decreased, but the thioacetamide-induced cirrhotic state had no effect on glutamate dehydrogenase or glutaminase activity. Glutamine synthetase activity was decreased in rats treated with thioacetamide for 4 or 12 weeks. These results are consistent with the hypothesis that the capacity for urea production from NH3 and amino acids is decreased in the development of cirrhosis.

Alanine Transaminase↗
PubMed1999

Characteristics of nitrogen metabolism in rats with thioacetamide-induced liver cirrhosis.

Female Sprague-Dawley rats were given 0.03% thioacetamide (TAA) in their drinking water daily for 4 or 12 weeks, and were then given normal water for 4 weeks after the end of a 12-week TAA treatment to investigate amino acid metabolism. In the malnourished precirrhotic stage (stage 1) and the malnourished cirrhotic stage (stage 2), the aromatic amino acids (AAA), Glu, Asp, Orn, Arg and Cit increased, and the branched-chain amino acids (BCAA) decreased slightly. Because these changes normalized in the well-nourished cirrhotic stage (stage 3), they might have resulted from impairment of hepatocytes and malnutrition. The net uptake of BCAA into the liver increased in stage 2, but the AAA uptake did not exceed that in normal controls. Portal venous plasma AAA increased to the same level as arterial plasma AAA. These results suggest that the decrease in BCAA was partially due to liver uptake and that the increase in AAA was induced by reduction of liver uptake and overproduction in extrahepatic tissues. The liver contents of BCAA and AAA were unchanged in all stages, so were fully utilized in the impaired liver. The increases in Glu, Asp, Orn and Cit might have resulted from overproduction in the liver, because these contents of the liver increased in stage 2. In conclusion, the changes in amino acid metabolism in rats with cirrhosis induced by TAA closely resemble those seen in human liver cirrhosis.

Amino Acids↗
PubMed1999

Revascularization and new bone formation in heat-treated bone grafts.

Human imnmunodeficiency virus (HIV) infection is one of the possible serious complications associated with bone allografts. In order to prevent infection, grafted bone is sterilized by various treatments. Heat treatment has attracted attention as a simple and practical method. We carried out a histological study of the influence of heat treatment on autogenic bone grafts. To eliminate the problem of antigenicity of grafted bone, we used autografts, not allografts. Three types of heat-treated autografts were employed: heat-treated at 60 degrees C for 30 min, at 80 degrees C for 10 min, and at 100 degrees C for 5 min; as a control, fresh autografts were replaced in the rabbits' ilium. One, 2, 4 and 8 weeks after grafting, we performed microangiography and prepared two types of samples: transparent and haematoxylin-eosin (H&E) stained. Then, using an image analyzer, we quantitatively measured revascularization and new bone formation in the grafted bone. The grafts heat-treated at 60 degrees C showed early and good revascularization and new bone formation, from 1 to 8 weeks. The grafts heat-treated at 80 degrees C showed relatively good revascularization and new bone formation. However, the grafts heat-treated at 100 degrees C showed unsatisfactory revascularization and bone formation, less than 40% of control 8 weeks after grafting. Therefore, heat treatment at 60-80 degrees C does not seriously affect revascularization and new bone formation.

Animals↗
PubMed1997

Giant vascular leiomyoma in the hand.

Vascular leiomyoma or angioleiomyoma is a benign solitary tumour that arises from the mediae layer of the vein walls. It is usually located in the wall of the uterus. We describe a 73-year-old man who presented with a slowly growing mass in the thenar region of his right hand which, on histological examination, was shown to be a giant vascular leiomyoma. This is extremely rare and we could find only about 100 such cases reported in English.

Aged↗
PubMed1996

Population of hepatic macrophages and response of perfused liver to platelet-activating factor during production of thioacetamide-induced cirrhosis in rats.

The response of hepatic macrophages and the effects of platelet-activating factor (PAF) in perfused liver were studied during production of experimental cirrhosis induced by thioacetamide (TAA) in female Sprague-Dawley rats. Within 4 weeks of TAA administration (300 mg/L drinking water), an increase in hepatic macrophage population and enlargement in cell size preceded the alterations characteristic of cirrhosis. During 12 weeks of TAA administration, the changes in hepatic macrophages were maintained and cirrhosis of the micronodular type developed with a marked increase in hydroxyproline content. Although TAA treatment for 4 weeks had no effect on oxygen consumption or hepatic portal pressure in the perfused liver, the increment in hepatic portal pressure and decrement in oxygen consumption induced by PAF in TAA-treated rats were double those in control rats. The amounts of prostaglandin D2 (PGD2) and thromboxane B2 (TxB2) in perfusate induced by PAF were seven- and fivefold greater, respectively, in TAA-treated rats than in control rats. Zymosan mimicked the effects of PAF. These results are consistent with the hypothesis that hepatic macrophages and PAF play important roles in the development of cirrhosis induced by TAA.

Animals↗
PubMed1996

Bone resorption by tartrate-resistant acid phosphatase-positive multinuclear cells isolated from rheumatoid synovium.

Inflammatory reactions in rheumatoid arthritis (RA) often cause severe joint destruction. However, the mechanism of bone destruction is still a matter of controversy. To determine whether multinuclear cells found in the rheumatoid synovium can resorb bone, isolated synovial cells were assessed for tartrate-resistant acid phosphatase (TRAP) staining and the ability to resorb bone in a dentine resorption assay. TRAP-positive multinuclear cells were found in six out of 10 samples. These six samples showed resorption pit formation on dentine slices. The other four samples did not form resorption pits. The results of this study demonstrate that TRAP-positive multinuclear cells isolated from the rheumatoid synovium form resorption pits on dentine slices. Our results suggest that inflamed synovial cells in rheumatoid joints might participate in bone destruction.

Acid Phosphatase↗
PubMed1996

Effect of jaw position and posture on forced inspiratory airflow in normal subjects and patients with obstructive sleep apnea.

OBJECTIVE: This study evaluated whether substantial airflow changes occur by changing both body posture and jaw position in normal subjects and patients with obstructive sleep apnea (OSA). DESIGN: A case-control design was utilized to assess group differences (OSA vs control) and each subject served as his/her own control subject to assess condition differences (jaw position and body posture changes). Subjects included 16 male patients with OSA (aged 33 to 71 years) whose conditions were diagnosed at the UCLA Sleep Disorders Laboratory with a polysomnographic recording, and 9 male non-OSA subjects (aged 22 to 52 years). The experimental intervention in the study involved alterations in body posture and jaw positioning. Airflow changes were determined using a spirometer that assessed the velocity of airflow during a forced inspiration. Subjects in this study all had the middle portion (25 to 75%) of their maximum forced inspiratory flow (FIF25-75) curve measured in three positions; (1) normal jaw position-upright body posture (N-U); (2) normal jaw position-supine body posture (N-S); and (3) protrusive jaw position-supine body posture (P-S). SETTING: The study was conducted at the UCLA Dental Clinical Research Center. RESULTS: Both groups had a significant decrease in their FIF25-75 upon reclining, and there were no significant group differences regarding the magnitude of this change. Both groups also had a nearly full recovery of their FIF25-75 airflow when their jaws were positioned forward while reclining. CONCLUSIONS: These data document that when a patient is in a supine position, a 100% protrusive jaw position allows significantly more inspiratory airflow to occur.

Adult↗
PubMed1996

Immunosuppressive effect of tacrolimus (FK-506). Bone xenografts in rabbits.

We examined the immunomodulatory effect of the macrolide antibiotic FK-506 (tacrolimus) in bone xenograft transplantation. Full-thickness pieces of iliac bone from mongrel dogs were transplanted into the iliac bone of Japanese white rabbits. FK-506 at a dose of 1.6 mg/kg/day was injected into the rabbits for 10 days after transplantation. In the animals treated with FK-506, inflammatory cell infiltration was remarkably reduced and revascularization accompanied by new bone formation occurred in the grafts. At 4 months after the transplantation, the formation of new bone and of mature new bone marrow were observed. In a control group, inflammatory cell infiltration was marked around the graft from 2 weeks after the transplantation. Revascularization from the recipient site to the graft in the control group was poor and only a small amount of new bone had formed at 4 months. Our findings suggest that short-term administration of FK-506 has a beneficial effect on experimental xenograft bone transplantation.

Animals↗
PubMed1996

Osteomesopycnosis: the first report from Japan.

We describe three sisters in a family who presented with a clinical form of osteomesopycnosis which is a rare, benign osteosclerotic bone disorder limited to the axial skeleton. It must be distinguished from other osteosclerotic conditions which carry a worse prognosis. This is the first report of the condition in a Japanese family, and we believe it to be the first to be identified in Asian races.

Adolescent↗
PubMed1995

Fine structure and distribution of lymphatics in the synovial membrane of monkey and human knee joints. A study using an enzyme-histochemical method.

The fine structure and distribution of lymphatics in the synovial membrane of monkey knee joints, and human knees with osteoarthritis and rheumatoid arthritis, were studied by light and electron microscopy using an enzyme-histochemical method. Whole mount preparations and tissue sections were doubly stained for 5'-nucleotidase and alkaline phosphatase. The 5'-nucleotidase positive lymphatics could be distinguished from the alkaline phosphatase positive blood vessels. In monkey specimens the 5'-nucleotidase lymphatics were densely distributed in the medial and lateral parts of the suprapatellar pouch and infrapatellar fat pad, in both the superficial and deep of the sublining cell layers. Collecting lymphatics were well developed in the deep fibrous layer and in the merging epimysium. In the knees with both types of arthritis, the patterns of distribution were the same as in the monkey. No lymphatics were found in well developed villi in rheumatoid arthritis, but many blood vessels were present.

Animals↗
PubMed1995

Grafted bone used in acetabular reconstruction: assessment by SPECT scintigraphy.

OBJECTIVE: To investigate incorporation of the grafted bone used for acetabular reconstruction. DESIGN: Single photon emission computed tomography (SPECT) was carried out at the 1st, 6th, and 12th month after the operation and the uptakes on serial SPECT scintigrams were normalized. The horizontal histogram of scintigraphic activity at the level of the central grafted bone in the coronal image was designated the profile curve. PATIENTS: Seven patients who had undergone bipolar hip arthroplasty for osteoarthritis of the hip were randomly selected. RESULTS AND CONCLUSION: Five of seven profile curves obtained at the 1st month demonstrated a single peak at the host-graft junction. The profile curve obtained at the 6th month showed two peaks at the host-graft junction and the periphery of the grafted bone in all patients. The profile curve at the 12th month showed slightly increased activity in the center of the grafted bone. This preliminary study demonstrates that comparison of the serial profile curves on SPECT is valuable in evaluating the progress of incorporation of the grafted bone in hip arthroplasty.

Acetabulum↗