Search PubMed⌕ Search

Biomedical subjects

S Iyama

Publications and source records attributed to S Iyama.

At least 37 records · Page 2Linked to original sources
PubMed1997

Histological comparison of early wound healing following dense hydroxyapatite granule grafting and barrier placement in surgically-created bone defects neighboring implants.

The purpose of this study was to examine early wound healing following grafting of dense hydroxyapatite granules (HA granules) and barrier placement in surgically-created bone defects surrounding implants. Eight healthy adult dogs with an average weight of 15 kg were used in this study. Thirty-two bone defects measuring 4 mm x 4 mm were removed with a surgical bur to form continuous bucco-lingual bone defects and 32 implants (16 titanium [Ti]) and 16 hydroxyapatite-coated [HA]) were then placed into the defects. Four implant groups were created: 1) grafting HA; 2) covering with an expanded polytetrafluoroethylene (ePTFE) membrane; 3) grafting HA and covering with ePTFE membrane; and 4) control (no treatment). Animals were sacrificed 28 days after surgery. Histological sections revealed large amounts of newly-formed bone in all bone defects surrounding the implants treated with ePTFE membranes alone. Fibrous encapsulation of HA granules was observed in the defects of the HA granules grafting group. In the group with grafting of HA granules and covering with ePTFE membranes, small amounts of bone tissue were observed among HA granules, but most HA granules were surrounded with fibrous tissue. Bone defects were completely filled with connective tissue in the control group. There were no differences in the histological findings between Ti and HA-coated implants in all cases. Histomorphometric data disclosed that the presence of HA granules in the bone defects significantly arrested bone formation. Our study suggests that the grafting of dense HA into bone defects surrounding implants will result in fibrous healing during the early healing stage.

Alveolar Bone Loss↗
PubMed1997

A study of the regional distribution of bone formed around hydroxyapatite implants in the tibiae of streptozotocin-induced diabetic rats using multiple fluorescent labeling and confocal laser scanning microscopy.

The present study was designed to compare the amount and regional distribution of bone formation around hydroxyapatite (HA) implants in normal (control) rats with that of animals with diabetes mellitus (DM), induced by streptozotocin 2 weeks prior to implant placement. Calcein (CAL), alizarin complexone (AL), and tetracycline (TC) were injected on the 7th, 14th, and 21st days after implantation, respectively, and the rats were sacrificed on the 28th day after implantation. Seventy-microns undecalcified sections of the HA-bone interface in both groups were then prepared for confocal laser scanning microscopy (CLSM) observation. In both groups, bone formation developed from the HA surface to the endosteum, periosteum, or bone marrow. In the control group, around the HA close to the endosteum and periosteum, the new bone showed an extensive lamination pattern of three color layers (CAL, AL, and TC), but in the DM group the labeling density of TC on the 21st day was low. In contrast, on the lateral part of the HA surface (away from the endosteum and periosteum), there was considerably less bone formation in the control group, and in the DM group it was almost completely suppressed. These findings indicate that bone formation around the HA was initiated from the HA surface in the control group, while in the DM group, bone formation along the lateral part of the HA away from the endosteum and periosteum was almost completely suppressed. Furthermore, it is also suggested that in the new bone along the HA close to the endosteum and periosteum, only calcification on the 21st day was depressed.

Animals↗
PubMed1997

The effects of diabetes on the interface between hydroxyapatite implants and bone in rat tibia.

We examined the influence of diabetes on the implant-bone interface of hydroxyapatite (HA) implants inserted transcortically and extending into the medullary canal of rat tibiae, and quantitatively assessed the differences in bone reaction using an image processing system. Forty male Wistar King A rats (aged 5 weeks) were used in this experiment; they were sacrificed 84 days after implant placement. Toluidine blue-stained undecalcified sections were prepared for histological observation and image analysis, and the labeled sections were observed by confocal laser scanning microscopy. The HA implants in the bone marrow area in the control group were completely encapsulated with a bone layer, and there were some osteoblast-like cells in the bone lacunae apposing the implant surface. The HA implants in the diabetes-induced (DI) group were partially surrounded with a thin bone layer, and there were some fibroblasts running parallel to the implant surface at areas of no bone contact. Quantitative evaluation indicated that the control group showed significantly higher bone contact rate, bone contact thickness, and bone contact area than the DI group. The DI group showed approximately 30% reduction in the percentage of bone contact and 50% reduction in the thickness and the area of surrounding bone tissue.

Animals↗
PubMed1997

Failing hollow implants examined by light microscopy and image processing.

The purpose of this study was to evaluate the radiologic, histologic, and histometric findings of three failing hollow implants. On periapical radiographs, these implants showed vertical bone loss up to the hollow portion around the implant. Examination of the histologic sections disclosed that the hollow portions of all the implants were almost filled with bone tissue, although slight bone resorption and presence of granulation tissue infiltrated with inflammatory cells was observed coronal to the hollow portion. Histometric analysis disclosed that the average percent bone contact was 93.1% in case 1, 90.9% in case 2, and 84.3% in case 3 and the average percent bone filling was 42.1%, 50.5%, and 33.8%, respectively. Consequently, there seems to be some potential for successful treatment of these implants because the destructive changes were limited to the coronal aspects of the implant.

Alveolar Bone Loss↗
PubMed1997

Abscess formation around a hydroxyapatite-coated implant placed into the extraction socket with autogenous bone graft. A histological study using light microscopy, image processing, and confocal laser scanning microscopy.

The purpose of this study was to evaluate the radiologic, histologic, and histometric findings for a retrieved hydroxyapatite (HA)-coated implant which had been placed into a fresh extraction socket with autogenous bone graft 3 months previously. A periapical radiography disclosed a vertical bone loss around the implant cervix. Examination of histologic section disclosed that granulation tissue including bone chips around the cervix, and newly-formed bone tissue around the grafted bone tissue on the HA coated surface. In the confocal laser scanning microscopic findings toluidine blue-negative bone tissue showed autofluorescence. Histometric analysis indicated that the average percent bone contact was 29.2% (ranged 26.4% to 34.1%). Suspected reasons for failure were an early exposure of the barrier membrane, its early removal, the implant placement into an infected site, inadequate antibiotic premedication, and/or poor control of infections around teeth prior to implant surgery and around implants before and after placement of barrier membrane.

Abscess↗
PubMed1997

Fully automated measurement of total iron-binding capacity in serum.

We established a method for fully automated measurement of total iron-binding capacity (TIBC) in serum without separation of the unbound excess iron after saturating serum transferrin. After saturation of serum transferrin with an excess amount of iron (first step), the unbound iron was eliminated by formation of a complex with ferrozine, which was used as a chromogenic reagent (second step). For the TIBC assay, iron dissociated from transferrin by shifting the pH to acidic was reacted with ferrozine, and the increase in the absorbance at 570 nm was measured (third step). Because the iron used as a calibrator, which was added to saturate transferrin, reacted completely with ferrozine in the second step (elimination of unbound iron), the change in the absorbance to generate a calibration factor could not be monitored in the third step. To solve this problem, we used N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA) to complex with the iron added to saturate transferrin in the second step. This made it possible to form an iron-ferrozine complex at acidic pH because iron was dissociated from HEDTA at acidic pH. The within-run CVs of this method were 0.66-2.43% at 17.7-77.0 mumol/L, and the day-to-day CVs were 1.06-1.57% at 29.9-60.4 mumol/L (n = 10). The correlation between the values obtained with this method (y) and those from the direct TIBC assay, which involved removal of unbound iron by ion-exchange resin (x), was: y = 0.963x + 0.29 mumol/L (r = 0.973, Sy/x = 2.83, n = 59), and with the TIBC values calculated from the serum iron concentrations and the unbound iron-binding capacities measured by a direct colorimetric method (x) was: y = 1.01x - 1.06 mumol/L (r = 0.994, Sy/x = 1.66, n = 51).

Blood Proteins↗
PubMed1996

A histologic evaluation of retrieved hydroxyapatite-coated blade-form implants using scanning electron, light, and confocal laser scanning microscopies.

We histologically examined seven hydroxyapatite-coated (HA) blade implants removed from patients. Four of them radiologically showed severe bone loss and were easily removed with an elevator. Three radiologically showed vertical bone loss and were removed by surgical procedure. Our histological evaluation indicated that coating separation from the HA implants had occurred, and HA coating resorption by bone tissues was suspected in an implant left in situ for 8 years. Several multinucleated giant cells were seen with a few released particles of HA coating at the point lacking bone contact with the HA coating. The presence of microorganisms on and in the HA coating layer was also noted.

Adult↗
PubMed1996

New enzymatic assay for calcium in serum.

We established a simple and rapid kinetic assay for measurement of calcium in serum by using urea amidolyase (EC 3.5.1.45) from yeast species. The method is based on inhibition of the enzyme by calcium. In the assay, we eliminated endogenous ammonium ion by use of glutamate dehydrogenase (GLDH; EC 1.4.1.4); then in the presence of urea amidolyase, urea, ATP, bicarbonate, magnesium, and potassium ions, ammonium ion production was inversely proportional to calcium ion concentration in serum. The concentration of ammonium ion formed was determined by adding GLDH to produce NADP+ in the presence of 2-oxoglutarate and NADPH; we then monitored the change of absorbance at 340 nm. The within-run CVs of this method were 1.7-3.2% (n = 10) at 1.53-3.08 mmol/L, respectively. Day-to-day (total) CVs were 2.8-4.1%. Analytical recovery was 92-112%. The presence of other ions, ascorbic acid, reduced glutathione, bilirubin, hemoglobin, citrate, lipemic material, or human serum albumin did not affect this assay system. The correlation between values obtained with our method (y) and o-cresolphthalein complexone method (CPC) (x) was: y = 1.001x + 0.077 mmol/L (r = 0.949, Sy[symbol: see text]x = 0.079, n = 100); with the other enzymatic method (x) it was: y = 0.952x + 0.021 mmol/L (r = 0.955, Sy[symbol: see text]x = 0.074, n = 100). The SEs for each method were: 0.025 mmol/L, our method; 0.023 mmol/L, CPC method; and 0.025 mmol/L, the other enzymatic method.

Adenosine Triphosphate↗
PubMed1992

Reciprocal changes in serum levels of immunoglobulins (IgG, IgA, IgM) and complements (C3, C4) in normal pregnancy and after delivery.

Sequential changes in serum levels of IgG, IgA, and IgM, and C3 and C4 during and after pregnancy were studied in 8 healthy women. Serum IgG decreased gradually during pregnancy, but increased markedly during the six months following delivery. Serum IgA and IgM levels also showed patterns similar to IgG. In contrast, C3 and C4 levels increased significantly and reached maximum levels in the last trimester during pregnancy, but decreased gradually for six months after delivery. Reciprocal changes between immunoglobulins and complements were clarified for the first time, and were suggestive of a compensatory autoregulatory mechanism in the suppression of the humoral immune system during pregnancy.

Adult↗
PubMed1991

[Converse changes in serum levels of immunoglobulins (IgG, A and M) and complement components (C3, 4) during pregnancy].

Sequential changes in serum levels of the immunoglobulins IgG, A and M and of the complements C3 and C4 during pregnancy and the postpartum period were studied in 8 healthy women. Serum IgG and A levels decreased gradually during pregnancy, but increased significantly during the first three months following delivery. Serum IgM level also decreased during pregnancy, reaching its minimum during the second trimester, but increased thereafter. In contrast, C3 and C4 levels increased significantly during pregnancy and reached their maximum levels during the last trimester. After delivery, levels of these two components decreased gradually for the next six months. The complement system may operate as a compensatory autoregulatory mechanism in the suppression of the humoral immune system during pregnancy.

Adult↗
PubMed1990

Digoxin-like immunoreactivity in Chinese medicine.

Immunoreactive digoxin-like activity was observed in Chinese medicine, KYUSHIN tablet, taken popularly in Japan without prescription. The antibodies used in the assays of digoxin reacted with Chan-su, the major effective component of KYUSHIN, which contained cardiotonic steroids with similar chemical structure as digoxin. One tablet of KYUSHIN had digoxin-like immunoreactivity equivalent to 1.9, 1.5, and 72 micrograms of digoxin measured by three different commercial kits. These different equivalences may be attributed to differences in cross-reactivity of the antibody used in the immunoassays. Two healthy volunteers took two KYUSHIN tablets three times a day, a typical dose, and digoxin-like immunoreactivity reached almost 0.4 micrograms/L in 0.5 day. Therapeutic drug monitoring should be interpreted carefully in patients taking Chinese medicines, many of which contain the Chan-su component.

Cross Reactions↗