Biomedical subjects

Y Iwayama

Publications and source records attributed to Y Iwayama.

At least 19 recordsLinked to original sources

PubMed2005

Gene expression and association analyses of LIM (PDLIM5) in bipolar disorder and schizophrenia.

We previously reported that expression level of LIM (ENH, PDLIM5) was significantly and commonly increased in the brains of patients with bipolar disorder, schizophrenia, and major depression. Expression of LIM was decreased in the lymphoblastoid cells derived from patients with bipolar disorders and schizophrenia. LIM protein reportedly plays an important role in linking protein kinase C with calcium channel. These findings suggested the role of LIM in the pathophysiology of bipolar disorder and schizophrenia. To further investigate the role of LIM in these mental disorders, we performed a replication study of gene expression analysis and performed genetic association studies. Upregulation of LIM was confirmed in the independent sample set obtained from Stanley Array Collection. No effect of sample pH or medication was observed. Genetic association study revealed the association of single nucleotide polymorphism (SNP)1 (rs10008257) with bipolar disorder. In an independent sample set, SNP2 (rs2433320) close to SNP1 was associated with bipolar disorder. In total samples, haplotype of these two SNPs was associated with bipolar disorder. No association was observed in case-control analysis and family-based association analysis in schizophrenia. These results suggest that SNPs in the upstream region of LIM may confer the genetic risk for bipolar disorder.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Synthetic sulfonolipids deduced from sulfonoquinovosyl diacylglycerols of sea urchin reduces hepatic ischemia-reperfusion injury in rats.

BACKGROUND: In hepatic surgery and liver transplantation, ischemia-reperfusion (I/R) is an unavoidable process, and protection against hepatic I/R injury is a major unresolved problem. In this study, we investigated whether 3-O-(6-deoxy-6-sulfono-beta-D-glucopyranosyl)-1,2-di-O-acylglycerol bound to saturated C18 fatty acids (beta-SQAG9), which was derived from sea urchin intestines, could reduce this injury. This agent was recently reported to have immunosuppressive effects in allogeneic rat skin grafts. MATERIALS & METHODS: Male Lewis rats were divided into two experimental groups. Group 1 rats were injected with SQAG9 (50 mg/kg) into the penile vein 15 minutes before the induction of ischemia and into the portal vein just reperfusion. The same amounts of normal saline were injected into rats in the control group (group 2). Each experimental groups included six rats. Seventy percent hepatic ischemia (20 minutes) was induced by occluding the blood vessels and bile duct with a vascular clamp. For examination of hepatic function, serum levels of aspartate aminotransferase, (AST) alanine transaminase (ALT), and lactic dehydrogenase (LDH) were measured. In addition, histological examination was also assessed. RESULTS: Three hours after reperfusion, the mean plasma concentration of AST, ALT, LDH in group 1 was suppressed compared with group 2. Six hours after reperfusion, the hepatic damage in group 1 was mild in comparison with that in group 2. CONCLUSIONS: Our data demonstrated that SQAG-9 reduced the warm hepatic I/R injury.

Animals↗

PubMed2001

Development of a new calcium phosphate cement that contains sodium calcium phosphate.

A cement powder consisting of sodium calcium phosphate, Na3Ca6(PO4)5, in addition to tetracalcium phosphate and beta-tricalcium phosphate was prepared by pulverizing blocks of 4 wt% sodium-, 11 wt% carbonate-containing apatite samples that were heated at 1700 degrees C for 5 h. When mixed with 30 wt% malic acid or citric acid at a powder liquid ratio of 3:1, the cement set in 3 or 7 min at room temperature with compressive strength being around 52 or 27 MPa. In HeLa-cell cultures, the cement mixed with malic acid was less cytotoxic than the cement mixed with citric acid, which was far less cytotoxic than a commercial carboxylate cement used as a negative control, suggesting malic acid to be superior to citric acid as a liquid in this regard. Similar findings were also obtained with osteoclasts, of which culture experiments clearly suggested that the number of osteoclasts on the cement mixed with malic acid was significantly greater than that on the cement mixed with citric acid. Since osteoclastic response to substrates could be used as a maker in evaluating their bioresorbability associated with osteoclasts, the above finding may suggest that the cement that is to be mixed with malic acid would be more useful as bone substitutes.

Animals↗

PubMed2001

Bisphosphonate inhibits alveolar bone resorption in experimentally-induced peri-implantitis in dogs.

The purpose of this study was to determine the effect of bisphosphonate on alveolar bone resorption in experimentally-induced peri-implantitis in beagle dogs. Experimental peri-implantitis was induced by ligation around the abutments, 6 months after placement of a fixture. Pamidronate (0.6 mg/kg) was injected intramuscularly every 3 days into each of 5 dogs. Another 5 dogs served as the control group and were injected with saline only. Peripheral blood and urine samples were collected every week up to 12 weeks after placement of the ligature. Standard X-rays were taken every week. Urinary deoxypyridinoline (DPD) and serum osteocalcin (OC) were evaluated by ELISA as markers of alveolar bone remodeling. X-ray films were analyzed with a computer image analyzer. After 12 weeks, the bone level was measured after removal of the gingival flap. The distance between the top surface of the fixture and the fundus of the defect was significantly lower in the Pamidronate group (1.59+/-0.55 mm, mean+/-SD) than in the control group (2.41+/-0.48 mm). Bone density analyzed from the X-ray films was significantly higher in the bisphosphonate group (69.2+/-8.7%, mean+/-SD) than in the control group (50.3+/-12.8%) after 2 to 8 weeks compared with the baseline value (100%). OC and DPD levels fluctuated during the experimental period. These findings suggest that bisphosphonate inhibits the progression of alveolar bone resorption during ligature-induced peri-implantitis in dogs.

Alveolar Bone Loss↗

PubMed2000

Asef, a link between the tumor suppressor APC and G-protein signaling.

The adenomatous polyposis coli gene (APC) is mutated in familial adenomatous polyposis and in sporadic colorectal tumors. Here the APC gene product is shown to bind through its armadillo repeat domain to a Rac-specific guanine nucleotide exchange factor (GEF), termed Asef. Endogenous APC colocalized with Asef in mouse colon epithelial cells and neuronal cells. Furthermore, APC enhanced the GEF activity of Asef and stimulated Asef-mediated cell flattening, membrane ruffling, and lamellipodia formation in MDCK cells. These results suggest that the APC-Asef complex may regulate the actin cytoskeletal network, cell morphology and migration, and neuronal function.

Adenomatous Polyposis Coli Protein↗

PubMed2000

Use of glass slides coated with apatite-collagen complexes for measurement of osteoclastic resorption activity.

This study was designed to evaluate the use of apatite-collagen complexes (ACC) coated onto glass slides for measurement of osteoclastic resorption activity. ACC-coated glass slides were prepared by immersion in beta-glycerophosphate solution for 7-14 days after glass slides coated with type I collagen had been treated with alkaline phosphatase and phosvitin. Osteoclast-containing cell suspensions were prepared from the long bones of 1-day-old rabbits and were seeded in medium 199 (containing 10% FBS) onto ACC-coated glass slides. After allowing the cells to attach for 1.5 h, the glass slides were incubated for periods of up to 96 h. The cells were observed by scanning electron microscopy and cytochemically for tartarate resistant acid phosphatase (TRAP) activity. Some slides were treated with FITC-phalloidin and anti-type I collagen antibody. TRAP-positive multinucleated cells were located in transparent spaces on the glass slides. These spaces did not stain immunohistochemically with anti-type I collagen antibody. Podosome formation was observed in the multinucleated cells facing the edge of the transparent spaces. The scanning electron microscopy demonstrated well-spread large cells located on the flattened surface on apatite particles covering the glass surface. Our results suggest that osteoclasts could resorb the apatite particles and coated collagen on the glass slide. The resorption lacunae appeared as transparent spaces, and the cytoskeleton of resorbing osteoclasts was observed in these spaces. ACC-coated glass slides could be useful for investigating the function and metabolic activities of osteoclasts.

Animals↗

PubMed2000

Long-term follow-up of periodontitis in a patient with Chédiak-Higashi syndrome. A case report.

Chediak-Higashi syndrome (CHS) is an extremely rare hereditary disease characterized by leukocyte dysfunction. We report on a 21-year-old woman who presented at the age 9 years with CHS and serious periodontal tissue destruction around erupted teeth. The patient had received systemic, radiographic, immunological, microbial, and clinical periodontal examinations since childhood. The chemotactic activity of neutrophils in the Boyden chamber assay was 22% of the control, and leukocyte bactericidal activity was one-third of the control. Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia were isolated from periodontal pockets. Periodontal treatment including oral hygiene was provided, followed by professional tooth cleaning from the age of 12 to 21 years. However, the mobility of teeth and the inflammation of periodontal tissue progressed. This CHS patient presented with periodontal disease of extremely early onset, which was resistant to periodontal treatment.

Actinobacillus Infections↗

PubMed1999

Osteoclastic responses to various calcium phosphates in cell cultures.

Disks made of hydroxyapatite, beta-tricalcium phosphate, carbonate apatite, tetracalcium phosphate, alpha-tricalcium phosphate, dicalcium phosphate dihydrate, and octacalcium phosphate were incubated in osteoclastic cell cultures for 2 days. The first five salts were sintered and the last two were compressed before incubation. Osteoclasts resorbed only the sintered carbonate apatite disks. However, osteoclasts were able to resorb octacalcium phosphate disks that were preincubated for 1 day in medium without cells, indicating that surface conditioning was important for osteoclastic resorption of this calcium phosphate. Although resorption did not occur, medium calcium and phosphorus changed to an appreciable extent after a 2-day incubation of beta-tricalcium phosphate, tetracalcium phosphate, alpha-tricalcium phosphate, and dicalcium phosphate dihydrate. These changes in the medium calcium and phosphate concentrations could explain why osteoclasts appeared to have lost their activity on these calcium phosphate disks and were not capable of resorbing them. With hydroxyapatite disks no changes were observed in the medium calcium and phosphorus before and after incubation. Moreover, the osteoclasts appeared to be essentially the same as with the sintered carbonate apatite disks and with bone slices used as a control. Nevertheless, no pits or lacunae were observed on the hydroxyapatite disks, indicating that sintered carbonate apatite should be superior to sintered hydroxyapatite as a bioresorbable bone substitute.

Animals↗

PubMed1999

Tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) stimulate osteoclastic bone resorption.

As both tissue inhibitor of metalloproteinases-1 (TIMP-1) and TIMP-2 have been reported to inhibit bone resorption, we examined whether TIMP-1 or TIMP-2 in fetal calf serum (FCS), with which culture media were supplemented, affected osteoclastic bone resorption in vitro. Contrary to our expectation, almost complete suppression of osteoclastic bone resorption was observed when both TIMP-1 and TIMP-2 were removed from the FCS. Bone resorption was, however, almost fully restored by the addition of recombinant TIMPs. TIMPs stimulate bone resorption at significantly lower concentrations (approximately ng/ml) than those (approximately micrograms/ml) required to inhibit bone resorption. To understand the mechanism of TIMP-dependent bone resorption, we counted and compared the number of tartrate-resistant acid phosphatase-(TRAP-) positive and multinuclear cells in cultures containing either 10% FCS or TIMP-1-free and/or TIMP-2-free FCS. There was essentially no difference in number among these, suggesting that the TIMP role seems to be related to the functional expression of osteoclasts. Metalloproteinase inhibitors, either BE16627B[L-N-(N-hydroxy-2-isobutylsuccinynamoyl)-seryl-L-val ine] or R94138 ¿N-methyl-(3S)-2-[(2R)-2-hydroxycarbamoylmethylundecanoyl] hexahydropyridazine-3-carboxamide¿, could not replace TIMPs, suggesting that the osteoclast-stimulating activity of TIMPs cannot be ascribed to merely their inhibitory effect on matrix metalloproteinases.

Acetamides↗

PubMed1998

Sintered carbonate apatites as bioresorbable bone substitutes.

The dissolution behavior of sintered carbonate apatite was investigated in a 10 mM/L acetic acid solution adjusted to pH 5.0 at 37 degrees C, and compared to that of sintered hydroxyapatite and bone apatite for the purpose of establishing some similarities between the physicochemical dissolution of apatite biomaterials in vitro and their ability to be resorbed by osteoclasts in vivo. Both the sintered carbonate apatite and the bone apatite dissolved to an appreciable extent. Their solution compositions changed in an almost identical manner until toward the end of the reaction. The solution compositions for sintered carbonate apatite at 30 s was comparable with that for sintered hydroxyapatite at 3.8 days with respect to the degree of supersaturation, indicating that the former specimen is much more soluble than the latter specimen. Osteoclasts which were obtained from the long bones of 1-day-old neonatal rabbits resorbed bone and sintered carbonate apatite, but not sintered hydroxyapatite. These findings suggest that sintered carbonate apatites, which have characteristics that can be favorably compared with those of bone, especially with respect to its reactivity to acid media, would be useful as bioresorbable bone substitutes.

Animals↗

PubMed1998

Use of hyaluronic acid binding protein for detection of hyaluronan in ligature-induced periodontitis tissue.

This study was designed to demonstrate, by use of biotin-labeled hyaluronic acid binding protein (HABP) and an avidin-enzyme system, the localization of hyaluronan (HA) in periodontal tissue of beagle dogs during experimentally induced periodontitis. Experimental periodontitis was induced in the dogs by ligation of the gingival sulcus. Experimental tissue was collected at 0, 3, 7 and 21 days after ligation. HA was revealed by strong staining in the intercellular space around epithelial cells and periodontal ligament, and by light staining in the gingival connective tissue. According to the progression of periodontal tissue breakdown, HA was detected in a small number of leukocytes and monocytes, on the surface of osteoclasts, the surface of alveolar bone, thickened endothelium and in epithelial cells related to rete peg formation. Streptomyces hyaluronidase-treated specimens gave negative staining. This study suggests that HA may be associated with the inflammatory reaction in experimental periodontitis tissue.

Alveolar Process↗

PubMed1997

Experimentally induced periodontitis in beagle dogs causes rapid increases in osteoclastic resorption of alveolar bone.

This study was undertaken to observe osteoclast differentiation related to inflammatory progression in aggressive periodontitis induced in beagle dogs by ligature of the gingival sulcus. To monitor osteoclastic activity, we used histochemical methods (staining for tartrate-resistant acid phosphatase [TRAP]) to visualize osteoclasts and their TRAP-positive precursors and biochemical methods (ELISA assay of pyridinium crosslinks) to detect bone matrix degradation products in gingival crevicular fluid (GCF), serum, and urine. For histochemical study, tissue specimens were prepared from 3 adult female beagle dogs induced with experimental periodontitis by silk ligature placement below the gingival margin of mandibular molars ligated for 3, 7, and 21 days. For biochemical study for pyridinoline measurement, the 24 mandibular molars of 4 male beagle dogs were ligated. GCF, urine, and serum were collected at day 0 and at 3, 7, 14, and 21 days after ligation. In the early inflammatory phase of ligature-induced periodontitis (day 3), TRAP+ mononuclear and TRAP+ multinucleated cells were present in the gingival connective tissue, and active bone-resorbing cells were found in excavated lacunae at the alveolar crest, but osteoclasts were not infiltrating the periodontal ligament during this early phase. During later stages of the inflammatory process (7 and 21 days), osteoclasts appeared at both the gingival and ligament side of the alveolar bone. Osteoclastic bone resorption appeared to be more severe on the bone surface at the gingival side than on the bone surface of the periodontal ligament side. Measurement of pyridinoline significantly increased in GCF and urine 3 days after ligation. The results suggested that bone at the crest of the alveolar bone is rapidly resorbed within 3 days of inducing experimental periodontitis.

Acid Phosphatase↗

PubMed1996

Mutation of the trkB gene encoding the high-affinity receptor for brain-derived neurotrophic factor in stroke-prone spontaneously hypertensive rats.

Brain-derived neurotrophic factor and its receptor, trkB, are thought to play a crucial role for protection against neuronal death induced by brain ischemia, such as in stroke. In the present study we found a missense mutation in the trkB gene from all of the five substrains of stroke-prone spontaneously hypertensive rats (SHRSP) that were examined. This mutation was not found in six out of seven hypertensive but stroke-resistant ancestral strains (SHR) of SHRSP, nor in any of seven strains of normotensive, non-stroke-prone strains. Hippocampal neurons, which are particularly vulnerable to damage in stroke, were shown to be more susceptible to ischemic damage in SHRSP than in either SHR or normotensive, stroke-resistant controls. The association of a mutated trkB gene with the stroke-prone genotype found in this study suggests that the trkB gene merits further study as a promising candidate gene for stroke.

Animals↗

PubMed1996

Formation of apatite-collagen complexes.

An apatite-collagen complex was prepared in calcium beta-glycerophosphate solutions at pH 9.0 and 37 degrees C with the purpose of developing new bone substitutes that more closely resemble bone than currently available materials. Reconstituted type I collagen as well as sheet collagen were crosslinked in the presence of alkaline phosphatase and egg-yolk phosvitin. The crosslinked collagens were immersed in daily-renewed calcium beta-glycerophosphate solutions for 2 and 4 weeks to induce the deposition of apatite on the collagen fibers. After 2 weeks of reaction, for example, apatites deposited approximately two times the crosslinked collagen in weight. With reconstituted collagen, the complex showed some elasticity but no apatite was visually observed to detach under deformation with fingers and forceps. The complex, moreover, did not disintegrate when immersed in saline or animal blood. Nevertheless, the complex resorbed with no evidence of cytotoxicity when implanted in muscle tissues. These findings suggest that the apatite-collagen complex prepared would be useful as bone substitutes, especially for periodontal osseous lesion repair and alveolar ridge augmentation.

Alkaline Phosphatase↗

PubMed1993

ELISA detection of glycosaminoglycan (GAG)-linked proteoglycans in gingival crevicular fluid.

The purpose of this study was to develop an ELISA method to detect chondroitin sulfate isomer-linked proteoglycans in gingival crevicular fluid (GCF), and to elucidate the role played by the glycosaminoglycans (GAGs) in GCF during experimentally-induced periodontitis in dogs. Experimental periodontitis was induced by placement of a silk ligature below the gingival margin of the molar teeth in 3 mongrel dogs. GCF was collected using microcapillary tubes at 0, 7, 21 and 60 days after ligature placement. To compare with GAG in GCF, bovine nasal cartilage proteoglycan monomer, dog's serum and supernatant of homogenized gingival tissue were prepared. Combination of monoclonal antibodies, 3B3 and 9A2, and specific enzymatic digestion made possible the identification of chondroitin 4 sulfate (C4S), chondroitin 6 sulfate (C6S) and dermatan sulfate (DS). The ELISA method detected very small amount of chondroitin sulfate (CS) isomers (15-1000 ng/ml of bovine nasal cartilage proteoglycan). The ELISA value of CS isomers in GCF was lower than that of homogenized gingival tissue but higher than that of the serum. The ELISA value of C4S, C6S and DS, although fluctuating, increased in proportion to the severity of the inflammation.

Animals↗

PubMed1990

Lectin-binding glycoconjugates and immunoreactive proteoglycans in resorption pits freshly excavated by isolated rabbit osteoclasts.

Staining with FITC-conjugated concanavalin A, wheatgerm agglutinin and peanut agglutinin demonstrated that abundant sugar residues are present in resorption pits produced in vitro and over the cell surface of rabbit osteoclasts resorbing bovine femoral bone slices. After chondroitinase ABC digestion the stubs of chondroitin 4-sulphate and dermatan sulphate could be detected in the resorption pits by monoclonal antibodies.

Animals↗

PubMed1990

[Immunohistochemical localization of the chondroitin sulfate proteoglycan in demineralized rat periodontal tissue].

We investigated the immunohistochemical localization of the chondroitin sulfates (chondroitin-4 sulfate, -6 sulfate and dermatan sulfate) in demineralized rat periodontal tissue using monoclonal antibodies (2-B-6, 3-B-3). Also, fixative and demineralized methods were established using these monoclonal antibodies. The result showed that the most effective combination of fixative and demineralized methods was 2% glutaraldehyde 1% para-formaldehyde and 5% EDTA. Chondroitin-4 sulfate and dermatan sulfate were widespread in gingival connective tissue and periodontal membrane, with an especially strong response of dermatan sulfate shown along collagen fiber bundles. Chondroitin-6 sulfate was located in peripheral blood vessels. In alveolar bone, chondroitin-4 sulfate and dermatan sulfate were found inside Hareversion canals, Volkman's canals and lacunae. Chondroitin-6 sulfate was localized at peripheral blood in alveolar bone. In cementum, chondroitin-4 sulfate and dermatan sulfate were found at lacunae of cellular cementum and a part of embedding Sharpey's fiber.

Animals↗

PubMed1990

Immunohistochemical study of chondroitin sulfate and dermatan sulfate proteoglycan in dental pulp and dentin.

We investigated the localization of chondroitin sulfate and dermatan sulfate proteoglycans in the dental pulp and dentin of rats, using a combination of an immunohistochemical technique coupled with specific enzymatic digestion. Chondroitin 4-sulfate and dermatan sulfate were found to be widespread in pulpal connective tissue, predentin and dentinal tubules. The response to predentin was found to be particularly strong. Chondroitin 6-sulfate was stretched in pulpal connective tissue and predentin, but showed only a weak response.

Animals↗