Search PubMed⌕ Search

Biomedical subjects

Toru Yamaguchi

Publications and source records attributed to Toru Yamaguchi.

18 recordsLinked to original sources
PubMed2006

Reduced expression of thrombospondins and craniofacial dysmorphism in mice overexpressing Fra1.

UNLABELLED: Fra1 transgenic (Tg) mice develop osteosclerosis and exhibit altered expression of bone matrix proteins. We found that expression of Thbs1 and Thbs2 was reduced in Fra1 Tg osteoblasts. Fra1 Tg and non-osteosclerotic Thbs1-/-Thbs2-/- mice share an edge-to-edge bite. Therefore, reduced expression of thrombospondins may contribute to craniofacial dysmorphism independently of osteosclerosis. INTRODUCTION: Tg mice overexpressing Fra1, a component of the transcription factor activator protein-1 (AP-1), show progressive osteosclerosis caused by cell autonomous abnormalities in osteoblasts. The expression of several bone matrix proteins, including matrix gla protein, is dysregulated in Fra1 Tg osteoblasts. MATERIALS AND METHODS: In osteoblastogenic cultures, altered bone matrix production by Fra1 overexpression was monitored using Alizarin red staining, quantitative RT-PCR, and Western blotting. Responsiveness to ovariectomy was examined by bone histomorphometry. Craniofacial parameters were measured on radiographs and using CT. RESULTS: Thrombospondin-1 (Thbs1) and thrombospondin-2 (Thbs2) were reduced in Fra1 Tg osteoblasts differentiated in vitro and in bones from Fra1 Tg mice. Despite alterations in bone matrix proteins, ovariectomy induces high turnover bone loss in Fra1 Tg mice as in wildtype mice. Fra1 Tg mice, as well as Thbs1-/- Thbs2-/- mice, which do not show osteosclerosis, exhibit an edge-to-edge bite phenotype associated with craniofacial dysmorphism. CONCLUSIONS: These data suggest that reduced expression of thrombospondins in Fra1 Tg mice underlies craniofacial dysmorphism, independent of osteosclerosis.

Animals↗
PubMed2006

[Treatment of primary osteoporosis in men].

Primary osteoporosis in men occurs less frequently and thus tends to be less noticed than that in women. However, once a femoral neck fracture occurs in men, patients are more likely to be disabled than women. Thus, implementing treatments of osteoporosis before the occurrence of femoral neck fractures is important in terms of men's quality of life. Several studies have shown that bisphosphonate is a mainstay of the treatment of the disorder, by increasing bone mineral density and reducing the risk of vertebral fractures.

Bone Density Conservation Agents↗
PubMed2005

Multiple vertebral fractures are associated with refractory reflux esophagitis in postmenopausal women.

We examined the frequency of multiple vertebral fractures (MVFs) and esophageal hiatal hernia (HH) in 18 Japanese postmenopausal women (74.1 +/- 9.9 years, mean +/- SD), with refractory reflux esophagitis (RRE) that had needed a proton pump inhibitor for more than 6 months to suppress symptoms such as heartburn and acid regurgitation, as well as in 57 control subjects without RE (71.4 +/- 5.9 years). MVFs (two or more VFs), HH, and both features were found in 11 (61%), 16 (89%), and 11 (61%) subjects, respectively, in the RRE group. All 11 patients with MVFs also had HH, suggesting their strong association. On the other hand, MVFs, HH, and both were found in 15 (26%), 23 (40%), and 8 (14%) subjects, respectively, in those without RE. The differences in frequencies of MVFs, HH, and both between the two groups were significant (chi2 = 7.3, 12.9, and 16.0; P = 0.015, 0.0009, and 0.0002, respectively). When univariate logistic regression analysis was performed with the presence of RRE as a dependent variable and the presence of MVFs, HH, and both as independent variables, MVFs, HH, and both were selected as indices affecting the presence of RRE (age-adjusted odds ratios: 4.34, 11.07, and 10.30; 95% confidential intervals: 1.40-13.45, 2.30-53.22, and 2.96-35.86; P = 0.0109, 0.0027, and 0.0002, respectively). These results show that the presence of MVFs is associated with the presence of RRE in Japanese postmenopausal women, and this association becomes more significant when HH is present. Thus, a kyphotic lumbar spine with MVFs may cause HH and RE by raising the intraabdominal pressure. As recent therapeutic agents for osteoporosis, alendronate and risedronate, are known to be very effective for suppressing the occurrence of new VFs, these agents may also prevent gastrointestinal disorders such as HH and RRE in osteoporotic women when administered to subjects without VFs.

Aged↗
PubMed2004

Involvement of calcium-sensing receptor in osteoblastic differentiation of mouse MC3T3-E1 cells.

We have previously shown that the extracellular calcium-sensing receptor (CaR) is expressed in various bone marrow-derived cell lines and plays an important role in stimulating their proliferation and chemotaxis. It has also been reported that the CaR modulates matrix production and mineralization in chondrogenic cells. However, it remains unclear whether the CaR plays any role in regulating osteoblast differentiation. In this study, we found that mineralization of the mouse osteoblastic MC3T3-E1 cells was increased when the cells were exposed to high calcium (2.8 and 3.8 mM) or a specific CaR activator, NPS-R467 (1 and 3 microM). Next, we stably transfected MC3T3-E1 cells with either a CaR antisense vector (AS clone) or a vector containing the inactivating R185Q variant of the CaR (DN clone) that has previously been shown to exert a dominant negative action. Alkaline phosphatase activities were decreased compared with controls in both the AS and DN clones. However, the levels of type I procollagen and osteopontin mRNA in the AS clone, as detected by Northern blotting, were almost the same as in the controls. On the other hand, the expression of osteocalcin, which is expressed at a later stage of osteoblastic differentiation, was significantly reduced in both the AS and DN clones. Mineralization was also decreased in both clones. In conclusion, this study showed that the abolition of CaR function results in diminishing alkaline phosphatase activity, osteocalcin expression, and mineralization in mouse osteoblastic cells. This suggests that the CaR may be involved in osteoblastic differentiation.

3T3 Cells↗
PubMed2004

Marked and sustained increase in bone mineral density after parathyroidectomy in patients with primary hyperparathyroidism; a six-year longitudinal study with or without parathyroidectomy in a Japanese population.

OBJECTIVE: Although many reports have demonstrated the sustained increase in bone mineral density (BMD) at trabecular sites in primary hyperparathyroidism (pHPT) after parathyroidectomy (PTX), there have been no data available on BMD changes over the long-term in pHPT patients with and without PTX in Japanese population. The present study was designed to investigate long-term BMD changes at both trabecular and cortical sites in Japanese pHPT patients with or without PTX. METHODS: The subjects were 97 patients who had been followed up in Kobe University Hospital for at least 1 year up to 6 years with or without PTX. PTX was recommended to all patients whose pathological parathyroid gland(s) could be determined by image diagnosis. BMD was measured at the lumbar spine (L2-L4) and at distal one-third of the radius (R1/3) by dual energy X-ray absorptiometry (QDR2000). Serum levels of calcium, alkaline phosphatase and parathyroid hormone (PTH) were determined at the time of the BMD measurement. RESULTS: Significant increases in any of the indices of BMD from the baseline values were observed within three months after PTX, followed by sustained increases over 6 years at L2-L4 even in postmenopausal women. Radial BMD also showed a marked increase six years after PTX. L2-L4 eventually reached the normal BMD but R1/3 did not. The percentage changes in L2-L4 were positively and significantly correlated with the preoperative PTH levels over the study period. However, the percentage changes in R1/3 showed a significant correlation with the preoperative PTH levels only 5 and 6 years after PTX. In the patients without PTX, no obvious changes in biochemical indices and BMD were observed over the six years. CONCLUSION: We demonstrated that PTX led to marked and sustained increases in BMD not only at L2-L4 but also at R1/3 in Japanese pHPT patients, including postmenopausal women. The preoperative PTH level could be a clinically useful index for predicting long-term BMD changes after PTX.

Bone Density↗
PubMed2003

Inactivation of menin, the product of the multiple endocrine neoplasia type 1 gene, inhibits the commitment of multipotential mesenchymal stem cells into the osteoblast lineage.

The physiological roles of menin, the product of the multiple endocrine neoplasia type 1 gene, are not known. Homozygous menin knockout mice exhibit cranial and facial hypoplasia. We, therefore, investigated the role of menin in the regulation of osteoblastic differentiation. Menin antisense oligonucleotides (AS-oligo) reduced endogenous menin expression in the C3H10T1/2 (10T1/2) mouse mesenchymal stem cells and antagonized alkaline phosphatase (ALP) activity and the expression of type I collagen, Runx2/cbfa1 (Runx2), and osteocalcin (OCN) induced by bone morphogenetic protein 2 (BMP-2). AS-oligo did not affect adipogenic markers (Oil red staining and PPARgamma expression) and chondrogenic markers (Alcian blue staining and type IX collagen) induced by BMP-2 in 10T1/2 cells. Menin co-immunoprecipitated with Smad1 and Smad5, and inactivation of menin antagonized BMP-2-induced transcriptional activity of Smad1/5. In osteoblastic MC3T3-E1 cells, AS-oligo affected neither BMP-2-stimulated ALP activity nor the expression of Runx2 and OCN. Stable inactivation of menin in MC3T3-E1 cells increased ALP activity, mineralization, and the expression of type I collagen and OCN. In 21-day cultures of MC3T3-E1 cells and BMP-2-treated 10T1/2 cells, endogenous menin expression increased up to day 14 and declined thereafter. These data indicate that menin inactivation specifically inhibits the commitment of pluripotent mesenchymal stem cells to the osteoblast lineage, mediated by menin and Smad1/5 interactions. Menin is important for both early differentiation of osteoblasts and inhibition of their later differentiation, and it might be crucial for intramembranous ossification.

3T3 Cells↗
PubMed2003

Functional giant parathyroid cyst with high concentration of CA19-9 in cystic fluid.

A 63-year-old man was admitted to our hospital for the evaluation of hypercalcemia and anterior neck mass. Laboratory findings revealed hypercalcemia, hypophosphatemia, and hypercalciuria, as well as elevated serum levels of parathyroid hormone (PTH) and alkaline phosphatase. Computerized tomography and magnetic resonance images showed that the mass contained a cystic area. Parathyroid scintigraphy using either 99mTc-sestamibi alone or 201Tl-chloride in conjunction with 99mTc-pertechnetate for thyroid image subtraction showed uptake of the radioactivity into the cyst wall, suggesting that the mass originated from the parathyroid. Fine needle aspiration biopsy revealed that the cyst fluid was serous and bloody with extremely high concentrations of both PTH and CA19-9. The patient was diagnosed as primary hyperparathyroidism caused by parathyroid cyst and cervical exploration was performed. The cyst was dissected away along with the right lobe of the thyroid gland. After tumor removal, serum calcium and PTH levels were normalized. Histological study showed that the tumor possessed malignant potential with capsular invasion as well as moderate cellular atypia with trabecular pattern in arrangement. Parathyroid cells in the wall of the cystic tumor were immunostained positively for CA19-9, suggesting that CA19-9 in the cyst fluid was produced from the cells.

CA-19-9 Antigen↗
PubMed2003

Trial to predict malignancy of affected parathyroid glands in primary hyperparathyroidism.

Parathyroid cancer is rare but relatively frequent in Japan compared to Western countries. Surgical parathyroidectomy is the primary choice for radical treatment of primary hyperparathyroidism (pHPT), hence it is important to distinguish malignant from benign tumor in the determination of surgical indication as well as method of operation. However, it is not easy to diagnose parathyroid cancer prior to operation. In the present study, we analyzed the background data, biochemical data and bone mineral density (BMD) of 131 patients with pHPT (111 benign and 20 malignant). BMD of the lumbar spine and mid-radius was measured by dual-energy X-ray absorptiometry. Serum levels of calcium, alkaline phosphatase (ALP), and parathyroid hormone (PTH) were significantly higher in malignant group compared to benign one. The extent of elevation of mid PTH seemed to be higher than that of intact PTH in malignant group. Age-, gender-, and race-adjusted BMD of distal one-third of radius was significantly decreased in malignant group compared to benign one, although that of lumbar spine was not significantly different between the two groups, indicating that osteopenia was marked in the region which was rich in cortical bone in malignant group. On the other hand, serum levels of calcium, ALP, and mid PTH as well as age were selected as predictors of malignancy in univariate logistic regression analysis, while serum level of intact PTH was not selected. In conclusion, radial BMD was lower in malignant group compared to benign one in pHPT. Serum levels of calcium, ALP and mid PTH were useful to predict malignancy of affected parathyroid glands in pHPT patients.

Alkaline Phosphatase↗
PubMed2003

[Not Available].

Explore the source record for details and available documents.

Journal Article↗
PubMed2003

[Not Available].

Explore the source record for details and available documents.

Journal Article↗
PubMed2002

The extracellular calcium Ca2+o-sensing receptor is expressed in myeloma cells and modulates cell proliferation.

The calcium-sensing receptor (CaR) is a G protein-coupled receptor that plays key roles in extracellular calcium ion (Ca(2+)(o)) homeostasis by enabling parathyroid, kidney, and other cells to directly "sense" changes in Ca(2+)(o). In multiple myeloma-associated bone disease, myeloma cells could raise the level of Ca(2+)(o) within their immediate vicinity in the bone marrow microenvironment, through their known capacity to cause bone destruction by stimulating osteoclastic bone resorption. Thus if myeloma cells expressed the CaR, they might sense these locally elevated levels of Ca(2+)(o), which could, in turn, potentially modify their function(s) in ways that could contribute to myeloma bone disease or other aspects of the pathophysiology of this disabling hematological malignancy. In this study, we examined the expression of the CaR in three myeloma cell lines, human U266, IM-9, and RPMI8226 cells. CaR protein was present in all three cell lines as assessed by immunocytochemistry and Western blot analysis using a monoclonal antibody specific for the CaR. Moreover, the use of reverse transcription-polymerase chain reaction (RT-PCR) with CaR-specific primers, followed by nucleotide sequencing of the amplified products, also identified CaR transcripts in the three cell lines. Exposure to known polycationic agonists of the CaR, including high Ca(2+)(o) (2.5mM), neomycin, and gadolinium (Gd(3+)) as well as a specific CaR activator, NPS R467, augmented cell proliferation in all three cell lines. RT-PCR revealed that U266 cells, but not IM-9 cells or RPMI8226 cells, expressed interleukin-6 (IL-6), the expression of which was not enhanced by treatments with CaR agonists. Therefore, taken together, our data first document the fact that the myeloma cell lines, U266, IM-9, and RPMI8226, all express CaR protein and mRNA. Moreover, the CaR expressed on myeloma cells could sense the locally high levels of Ca(2+)(o) in the vicinity of sites of osteoclastic bone resorption and stimulate their proliferation in an IL-6-independent manner. These processes may result in promoting further growth of the tumor and aggravating the associated bone disease.

Animals↗
PubMed2002

Activations of ERK1/2 and JNK by transforming growth factor beta negatively regulate Smad3-induced alkaline phosphatase activity and mineralization in mouse osteoblastic cells.

Transforming growth factor (TGF) beta inhibits alkaline phosphatase (ALP) activity and mineralization in mouse osteoblastic MC3T3-E1 cells, whereas local administration of TGF-beta stimulates bone formation in vivo. We recently demonstrated that Smad3, a TGF-beta signaling molecule, promotes ALP activity and mineralization in MC3T3-E1 cells. Moreover, the target disruption of Smad3 in mouse is reported to cause a decrease in bone mineral density. These findings indicate that Smad3 plays an important role in the regulation of bone formation. However, why the effects of TGF-beta and Smad3 on ALP activity and mineralization are different remains unknown. The purpose of the present study is to clarify the role of mitogen-activated protein kinase (MAPK) in TGF-beta and Smad3 pathways in osteoblast. TGF-beta activated extracellular signal-regulated kinases/p42/p44 (ERK1/2), p38 MAPK, and c-Jun N-terminal kinase (JNK) in mouse osteoblastic MC3T3-E1 cells. The expression of dominant negative type Smad3, Smad3DeltaC, affected neither TGF-beta-activated MAPKs nor TGF-beta-inhibited ALP activity. Specific inhibitors of ERK1/2 activation (PD98059 and U0126), as well as JNK inhibitors (curcumin and dicumarol) antagonized the inhibitory effects of TGF-beta on ALP activity and mineralization, whereas the specific inhibitor of p38 MAPK (SB203580) did not affect them. PD98059 and curcumin enhanced Smad3-induced ALP activity and mineralization, whereas SB203580 inhibited them. In the luciferase reporter assay using 3TP-lux with the specific Smad3-responsive element, PD98059, and curcumin enhanced TGF-beta- and Smad3-induced transcriptional activity in MC3T3-E1 cells. On the other hand, TGF-beta-induced production of type I collagen was antagonized by curcumin but not by PD98059. The present study indicated that TGF-beta-responsive ERK1/2 and JNK cascades negatively regulate Smad3-induced transcriptional activity as well as ALP activity and mineralization in osteoblasts.

Alkaline Phosphatase↗
PubMed2002

Familial hypocalciuric hypercalcemia caused by an R648stop mutation in the calcium-sensing receptor gene.

In this study, we report an 84-year-old female proband in a Japanese family with familial hypocalciuric hypercalcemia (FHH) caused by an R648stop mutation in the extracellular calcium-sensing receptor (CaR) gene. At the age of 71 years, she presented with hypercalcemia (11.4 mg/dl), hypocalciuria (Cca/Ccr = 0.003), hypermagnesemia (2.9 mg/dl), and a high-serum parathyroid hormone (PTH) level (midregion PTH, 3225 [160-520] pg/ml). At the age of 74 years, a family screening was carried out and revealed a total of 9 hypercalcemic individuals (all intact PTH values <62 pg/dl) among 17 family members tested, thus, being diagnosed as FHH. Two and one-half of three clearly enlarged parathyroid glands were resected, because persistently high PTH levels (intact PTH, 292 pg/ml; midregion PTH, 5225 pg/ml) and the presence of a markedly enlarged parathyroid gland by several imaging modalities (ultrasonography, computed tomography [CT], magnetic resonance imaging [MRI], and subtraction scintigraphy) suggested coexistent primary hyperparathyroidism (pHPT); however, hypercalcemia persisted postoperatively. Histological and immunohistochemical examination revealed that the resected parathyroid glands showed lipohyperplasia as well as normally expressed Ki67, vitamin D receptor (VDR), and the CaR. Sequence analysis disclosed that the proband and all affected family members had a heterozygous nonsense (R648stop) mutation in the CaR gene. This mutation is located in the first intracellular loop; thus, it would be predicted to produce a truncated CaR having only one transmembrane domain (TMD) and lacking its remaining TMDs, intracellular loops, and C-terminal tail. Western analysis of biotinylated HEK293 cells transiently transfected with this mutant receptor showed cell surface expression of the truncated protein at a level comparable with that of the wild-type CaR. The mutant receptor, however, exhibited no increase in intracellular free calcium concentration (Ca2+i) when exposed to high extracellular calcium concentrations (Ca2+o). The proband's clinical course was complicated because of associated renal tubular acidosis (RTA) and nephrotic syndrome. However, it was unclear whether their association affected the development of elevated serum PTH and parathyroid gland enlargement. This report is the first to show that an R648stop CaR mutation yields a truncated receptor that is expressed on the cell surface but is devoid of biological activity, resulting in FHH.

Base Sequence↗
PubMed2002

Smad3 promotes alkaline phosphatase activity and mineralization of osteoblastic MC3T3-E1 cells.

Transforming growth factor (TGF) beta is abundantly stored in bone matrix and appears to regulate bone metabolism. Although the Smad family proteins are critical components of the TGF-beta signaling pathways, the roles of Smad3 in the expression of osteoblastic phenotypes remain poorly understood. Therefore, this study was performed to clarify the roles of Smad3 in the regulation of proliferation, expression of bone matrix proteins, and mineralization in osteoblasts by using mouse osteoblastic cell line MC3T3-E1 cells stably transfected with Smad3. Smad3 significantly inhibited [3H]thymidine incorporation and fluorescent intensity of the MTT-dye assay, compared with empty vector. Moreover, Smad3 increased the levels of type I procollagen, osteopontin (OPN), and matrix Gla protein (MGP) mRNA in Northern blotting. These effects of Smad3 mimicked the effects of TGF-beta on the same cells. On the other hand, Smad3 greatly enhanced ALP activity and mineralization of MC3T3-E1 cells compared with empty vector, although TGF-beta inhibited ALP activity and mineralization of wild-type MC3T3-E1 cells. A type I collagen synthesis inhibitor L-azetidine-2-carboxylic acid, as well as osteocalcin (OCN), significantly antagonized Smad3-stimulated ALP activity and mineralization of MC3T3-E1 cells. In conclusion, this study showed that in mouse osteoblastic cells, Smad3 inhibited proliferation, but it also enhanced ALP activity, mineralization, and the levels of bone matrix proteins such as type I collagen (COLI), OPN, and MGP. We propose that Smad3 plays an important role in osteoblastic bone formation and might help to elucidate the transcriptional mechanism of bone formation and possibly lead to the development of bone-forming drugs.

Alkaline Phosphatase↗
PubMed2002

Plasma lipids and osteoporosis in postmenopausal women.

Many clinical studies have shown that osteoporosis is associated with atherosclerosis and cardiovascular death. Although both high plasma levels of low density lipoprotein cholesterol (LDL-C) and low plasma levels of high density lipoprotein cholesterol (HDL-C) are known to be risk factors for atherosclerosis, it is unclear whether such lipid derangements are also associated with the pathogenesis of osteoporosis. In this study, we evaluated the relationships between plasma levels of total C, LDL-C, HDL-C, or triglyceride (TG) versus bone mineral density (BMD) at the lumbar spine, femoral neck, radius, or total body as well as the presence of vertebral fractures in 214 Japanese postmenopausal women (age range, 47-86 years, mean 62.7). Multiple regression analysis was performed between BMD at each skeletal site versus each lipid level adjusted for age, years after menopause, body mass index (BMI), and %fat. Plasma LDL-C levels were significantly and inversely correlated with the absolute values of both one-third radial (1/3R) and distal radial (UDR) BMD (p<0.01), and tended to be inversely correlated with the absolute values of L-BMD (p=0.051). In contrast, plasma HDL-C levels were significantly and positively correlated with the absolute values of L, 1/3R and UDR BMD (p<0.05). On the other hand, plasma TG levels were significantly lower in women with vertebral fractures than in those without fractures (97.0+/-36.5 vs. 126.4+/-65.8 mg/dl, mean+/-SD, p<0.05). When multivariate logistic regression analysis was performed with the presence of vertebral fractures as a dependent variable and each lipid level adjusted for age, years after menopause, BMI, and %fat as independent variables, TG alone was selected as an index affecting the presence of vertebral fractures (odds ratio: 0.51, 95% confidential interval: 0.29-0.89 per SD increase, p<0.05). Our study showed that plasma LDL-C and HDL-C levels were inversely and positively correlated with both R- and L-BMD values, respectively, while low plasma TG levels were associated with the presence of vertebral fractures in postmenopausal women. Thus, plasma lipids might be related to bone mass and bone fragility, and might be the common factor underlying both osteoporosis and atherosclerosis.

Aged↗
PubMed2002

[Osteoporosis and vascular calcification].

Many clinical studies have shown that osteoporosis is associated with atherosclerosis and cardiovascular death. Plasma lipids might be related to bone mass and bone fragility, and might be the common factor underlying both osteoporosis and atherosclerosis. It is interesting that statins, estrogens, and nitrogen-containing bisphosphonates have similar stimulatory effects on bone mass, because all of them are known to reduce LDL-cholesterol (C) and increase HDL-C in the plasma. Thus, these two disorders might be related to each other in terms of pathogenesis and therapeutic agents.

English Abstract↗
PubMedDate not supplied

Limb salvage treatment for congenital deficiency of the tibia.

Nine limb salvage treatments were performed in 7 patients with congenital deficiency of the tibia. All feet showed equinovarus deformity and were centralized in a slightly equinus position by placing the distal end of the fibula into the posterior facet of the calcaneus. Tibiofibular fusion was performed in 4 patients with partial deficiency, and fibular transfer (fibular centralization; Brown procedure) in 5 with complete deficiency of the tibia. Callus distraction lengthening was performed repeatedly for leg-length discrepancy on either the femur or the centralized fibula. Satisfactory functional and cosmetic results were obtained in all limbs with partial deficiency, whereas in limbs with completely deficiency, none of the 5 knees treated by fibular transfer achieved a satisfactory functional result because of insufficient quadriceps strength, progressive knee flexion contracture, and persistent ligamentous instability. Nevertheless, in these 5 cases, all patients were ultimately able to withstand weight-bearing.

Adolescent↗