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S Yoshiki

Publications and source records attributed to S Yoshiki.

At least 37 records · Page 2Linked to original sources
PubMed1992

1 alpha,25-dihydroxyvitamin D3 regulates in vivo production of the third component of complement (C3) in bone.

We previously reported that 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25-(OH)2D3] specifically stimulates production of the third component of complement (C3) by murine osteoblastic cells and marrow-derived stromal cells (ST2) in vitro. In the present study we examined tissue-specific production of C3 in vivo in vitamin D-deficient mice, some of which received supplemental 1 alpha,25-(OH)2D3. Western blot analysis indicated that the C3 protein band in bone was undetectable in vitamin D-deficient mice, but became distinct 48 h after 1 alpha,25-(OH)2D3 administration. The mRNA expression of C3 in bone was also undetectable in vitamin D-deficient mice and appeared as early as 24 h after 1 alpha,25-(OH)2D3 administration. mRNA expression apparently preceded the appearance of C3 protein. In contrast, there was no significant difference in the expression of hepatic C3 mRNA among normal mice fed laboratory chow and vitamin D-deficient mice with and without 1 alpha,25-(OH)2D3 administration. The serum concentration of C3 in vitamin D-deficient mice was almost identical to that in normal mice and was unchanged after 1 alpha,25-(OH)2D3 administration. 1 alpha,25-(OH)2D3 receptor (VDR) mRNAs were detected in the kidney and intestine, whereas no appreciable mRNA expression of VDR occurred in the liver. Osteopontin mRNA was expressed in response to 1 alpha,25-(OH)2D3 in the kidney, but not in the intestine. Immunohistochemical studies showed that in normal mice, the C3 protein was located mainly in the periosteal regions of calvaria and on the surfaces of bone trabeculae in the tibial metaphyses. These results demonstrate that 1 alpha,25-(OH)2D3 tissue-specifically regulates in vivo production of C3 in bone. The production of bone C3 cannot be attributed to the presence of VDR alone, and we speculate that other tissue-specific factors are required.

Animals↗
PubMed1991

cDNA and deduced amino acid sequence of mouse matrix gla protein: one of five glutamic acid residues potentially modified to gla is not conserved in the mouse sequence.

A cDNA library was constructed using the mouse osteoblastic cell line MC3T3-E1 treated with 1 alpha,25-dihydroxyvitamin D3, based on the finding that the treatment increased ninefold the expression of 0.7 kb matrix gla protein (MGP) mRNA. cDNA clones encoding mouse MGP were isolated from the library. The nucleotide sequence showed an open reading frame of 312 nucleotides encoding 104 amino acids. Murine MGP shared 84-89% amino acid sequence homology with bovine, rat, and human MGP. However, there are five glutamic acid residues potentially modified to gamma-carboxyglutamic acid (gla) in those species; in murine MGP, lysine replaced glutamic acid 37. Also, an extra tyrosine was added at the carboxyl terminus. The significance of the substitution is discussed in relation to the gamma-carboxylation sites in MGP protein.

Amino Acid Sequence↗
PubMed1991

Putrescine is involved in the vitamin D action in chick intestine.

We have reported that a single injection of 1 alpha,25-dihydroxyvitamin D3 into vitamin D-deficient chicks produces a marked increase of putrescine accumulation in the duodenum from two different sources, ornithine and spermidine. In the present study, the effects of putrescine depletion and its supplementation on duodenal villus length and calcium absorption were examined in newborn and 5-week-old chicks. Administering either alpha-difluoromethylornithine, a specific inhibitor of ornithine decarboxylase, or N1,N4-bis(2,3-butadienyl)-1,4-butanediamine, a specific inhibitor of polyamine oxidase, to newborn chicks significantly decreased the duodenal content of putrescine and calcium transport activity. The putrescine depletion also induced shortening of the duodenal villus length. The inhibition of calcium absorption and villus length in the putrescine-depleted chicks was almost completely restored by administering putrescine to the birds. The effect of the putrescine depletion and its supplementation on the duodenal villus length and the calcium absorption was reproduced in 5-week-old vitamin D-deficient chicks given vitamin D3 or 1 alpha,25-dihydroxyvitamin D3. These results clearly indicate that putrescine is somehow involved in the vitamin D action in maintaining the morphological and functional development of the intestinal villus mucosa.

Acetyltransferases↗
PubMed1991

Recombinant human bone morphogenetic protein-2 stimulates osteoblastic maturation and inhibits myogenic differentiation in vitro.

The in vitro effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on osteogenic and myogenic differentiation was examined in two clonal cell lines of rat osteoblast-like cells at different differentiation stages, ROB-C26 (C26) and ROB-C20 (C20). The C26 is a potential osteoblast precursor cell line that is also capable of differentiating into muscle cells and adipocytes; the C20 is a more differentiated osteoblastic cell line. Proliferation was stimulated by rhBMP-2 in C26 cells, but inhibited in C20 cells. rhBMP-2 greatly increased alkaline phosphate (ALP) activity in C26 cells, but not in C20 cells. The steady-state level of ALP mRNA was also increased by rhBMP-2 in C26 cells, but not in C20 cells. Production of 3',5'-cAMP in response to parathyroid hormone (PTH) was dose-dependently enhanced by adding rhBMP-2 in both C26 and C20 cells, though the stimulatory effect was much greater in the former. There was neither basal expression of osteocalcin mRNA nor its protein synthesis in C26 cells, but they were strikingly induced by rhBMP-2 in the presence of 1 alpha,25-dihydroxyvitamin D3. rhBMP-2 induced no appreciable changes in procollagen mRNA levels of type I and type III in the two cell lines. Differentiation of C26 cells into myotubes was greatly inhibited by adding rhBMP-2. The inhibitory effect of rhBMP-2 on myogenic differentiation was also observed in clonal rat skeletal myoblasts (L6). Like BMP-2, TGF-beta 1 inhibited myogenic differentiation. However, unlike BMP-2, TGF-beta 1 decreased ALP activity in both C26 and C20 cells. TGF-beta 1 induced neither PTH responsiveness nor osteocalcin production in C26 cells, but it increased PTH responsiveness in C20 cells. These results clearly indicate that rhBMP-2 is involved, at least in vitro, not only in inducing differentiation of osteoblast precursor cells into more mature osteoblast-like cells, but also in inhibiting myogenic differentiation.

Alkaline Phosphatase↗
PubMed1991

Acid phosphatase activity is detected preferentially in the osteoclastic lineage by pre-treatment with cyanuric chloride.

We previously reported a simple method to detect osteoid matrices in decalcified bone sections by pre-treatment with cyanuric chloride. We have applied this technique to identify osteoclasts and their precursors in rats. In JB-4 sections prepared from untreated bone tissues with cyanuric chloride, both acid phosphatase (ACP) and tartrate-resistant acid phosphatase (TRAP) were found not only in osteoclasts and bone marrow mononuclear cells but also in osteoblasts. In contrast, treatment of bones with cyanuric chloride resulted in staining ACP preferentially in osteoclasts and mononuclear cells adjacent to the bone surface. In the osteoclasts and most of the ACP-positive mononuclear cells, autoradiography showed calcitonin binding. Decalcification with EDTA did not affect the staining for ACP activity in bones treated with cyanuric chloride. It was possible to simultaneously identify ACP and osteoid matrix in a decalcified section. In soft tissues without treatment with cyanuric chloride, both ACP and TRAP were detected in splenic macrophages, alveolar macrophages, and proximal convoluted ducts in kidney. Neither ACP nor TRAP was found in these cell types in the tissues treated with cyanuric chloride. This procedure provides a new, simple method to identify a more restricted population in the osteoclastic lineage than that detected by TRAP staining.

Acid Phosphatase↗
PubMed1990

IL-6 is produced by osteoblasts and induces bone resorption.

To examine the possible involvement of IL-6 in bone metabolism, a mouse osteoblastic cell line (MC3T3-E1) and primary osteoblast-like cells from fetal mouse calvaria were cultured with several systemic and local bone-resorbing agents and their expression of IL-6 mRNA was determined. Local bone-resorbing agents such as IL-1 alpha, IL-1 beta, TNF-alpha, and LPS greatly induced IL-6 mRNA expression in both MC3T3-E1 cells and primary osteoblast-like cells. Parathyroid hormone slightly increased expression of IL-6 mRNA in primary osteoblast-like cells but not in MC3T3-E1 cells. Neither IL-6 nor 1 alpha,25-dihydroxyvitamin D3 increased expression of IL-6 mRNA in either of the osteoblast-like cells. In agreement with the expression of IL-6 mRNA, biologically active IL-6 was produced in response to the treatment with IL-1 alpha, TNF-alpha, and LPS in MC3T3-E1 cells. Adding IL-6 dose dependently stimulated the release of 45Ca from prelabeled fetal mouse calvaria. Simultaneously adding suboptimal concentrations of IL-6 and IL-1 alpha induced bone resorption cooperatively. In accord with the increase in the release of 45Ca by IL-6, there were three times as many osteoclasts in the bone sections of calvaria cultured with IL-6 for 5 days as in the controls. IL-6 slightly suppressed alkaline phosphatase activity and collagen synthesis in MC3T3-E1 cells. These results indicate that IL-6 is also produced by osteoblasts, preferentially in response to local bone-resorbing agents, and it induces bone resorption both alone and in concert with other bone-resorbing agents.

Alkaline Phosphatase↗
PubMed1990

The non-osteogenic mouse pluripotent cell line, C3H10T1/2, is induced to differentiate into osteoblastic cells by recombinant human bone morphogenetic protein-2.

The possibility that the non-osteogenic mouse pluripotent cell line, C3H10T1/2 (10T1/2), could be induced to differentiate into osteogenic cells by various hormones and cytokines was examined in vitro. Of a number of agents tested, recombinant human bone morphogenetic protein-2 (rhBMP-2) and retinoic acid induced alkaline phosphatase (ALP) activity in 10T1/2 cells. rhBMP-2 also induced mRNA expression of ALP in the cells. Dexamethasone, 1 alpha, 25-dihydroxyvitamin D3, transforming growth factor-beta 1 and insulin-like growth factor-I did not stimulate ALP activity. Treatment with rhBMP-2 greatly induced cAMP production in response to parathyroid hormone in 10T1/2 cells. No ALP activity was induced in NIH3T3 fibroblasts treated with rhBMP-2 or retinoic acid. These results indicate that 10T1/2 cells have a potential to differentiate into osteogenic cells under the control of BMP-2.

1-Methyl-3-isobutylxanthine↗
PubMed1989

[Study of the penetration of extrinsic tracers into exposed cementum in vitro].

The purpose of the experiment was to study the possible penetration of extrinsic tracers with different molecular weights into exposed cementum in vitro and pathway of penetration. 75 human extracted teeth-55 periodontally diseased teeth and 20 embedded 3rd molars-were used. Each tooth was maintained in 0.005% fluorecein isothiocyanate (FITC) solution (M.W. 400), 0.05% FITC conjugated peroxidase solution (M.W. 40,000), or 0.01% FITC conjugated human IgG solution (M.W. 160,000) for 10 days. Morphological observations were made by means of fluorescence microscopy. Other extracted teeth were maintained in 0.05% microperoxidase solution (M.W. 1,900) for 5 days. Observations were then made using the TEM, and micrographs were taken and analyzed with an image analyzer. As a result, solutions of higher molecular weight showed lower penetration, and unexposed cementum showed a tendency toward greater penetration. Furthermore, the penetration of tracers on the surface of the cementum was along collagen fibers, but in the inner cementum, was into cementocyte lacunae and canaliculi.

Dental Cementum↗
PubMed1988

A differentiation-inducing factor produced by the osteoblastic cell line MC3T3-E1 stimulates bone resorption by promoting osteoclast formation.

We have reported that the differentiation-inducing factor (DIF) is present in conditioned medium of mouse osteoblast-like cell (MC3T3-E1) cultures. In the present study, the DIF from conditioned medium of MC3T3-E1 cells was partially purified and its biologic activity was examined. The DIF was purified by monitoring the induction of phagocytic activity of mouse myeloblastic leukemia cells (M1). The DIF induced differentiation of not only M1 cells but also mouse myelomonocytic cells (WEHI-3). Furthermore, the DIF increased the in vitro bone-resorbing activity and the osteoclast number in mouse calvaria. The increases were inhibited by the addition of either salmon calcitonin or indomethacin. When mouse bone marrow cells were cultured with the DIF for 8 days, formation of osteoclast-like multinucleated cells was stimulated dose dependently. The DIF from MC3T3-E1 cells appeared to be different from interleukin-1 (IL-1), tumor necrosis factor (TNF), and transforming growth factor beta (TGF-beta). These results suggest that the DIF partially purified from osteoblast-like cell cultures stimulates osteoclastic bone resorption by promoting differentiation and fusion of osteoclast progenitors to form multinucleated osteoclasts.

Animals↗
PubMed1988

Osteoclast-like cell formation and its regulation by osteotropic hormones in mouse bone marrow cultures.

We developed a mouse bone marrow culture system to examine the process of osteoclast-like multinucleated cell formation from its progenitors. When mouse marrow cells were cultured for 8 days with 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25-(OH)2D3, 10(-10) to 10(-7) M] or human PTH (1-34) (25-100 ng/ml), tartrate-resistant acid phosphatase (TRACP)-positive multinucleated cells formed. No TRACP-positive multinucleated cells appeared in the absence of these hormones. 1 alpha,25-(OH)2D3 and PTH also increased the number of the clusters of TRACP-positive mononuclear cells. Time course studies showed that these TRACP-positive mononuclear cell clusters appeared before the formation of TRACP-positive multinucleated cells, suggesting that the TRACP-positive mononuclear cells are precursors of the multinucleated cells. Salmon calcitonin markedly inhibited the formation of TRACP-positive multinucleated cells but not TRACP-positive mononuclear cell clusters induced by 1 alpha,25-(OH)2D3 or PTH. TRACP-positive mononuclear cells and multinucleated cells were rarely stained for nonspecific esterase, but some mononuclear cells were positively stained for both nonspecific esterase and TRACP. More that 90% of the TRACP-positive mononuclear cell clusters and multinucleated cells were found near colonies of alkaline phosphatase-positive mononuclear cells (possibly osteoblasts). When marrow mononuclear cells were cultured on sperm whale dentine slices in the presence of 1 alpha,25-(OH)2D3 or PTH, numerous resorption lacunae were formed. These results suggest that 1) TRACP-positive multinucleated cells formed in response to osteotropic hormones in mouse marrow cultures satisfy most of the criteria of osteoclasts, and 2) osteoblasts may play an important role in osteoclast formation.

Acid Phosphatase↗
PubMed1986

Bone in the marmoset: a resemblance to vitamin D-dependent rickets, type II.

The common marmoset, a New World monkey, requires a large amount of vitamin D3 to maintain its normal growth. This monkey is reported to have an end-organ resistance to 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3). In this study, the bone morphology of marmosets fed a high vitamin D3 diet (intake of vitamin D3, 110 IU/day/100 g of body weight) was compared by X-ray and histological examinations with that of rhesus monkeys (Old World monkey) fed a normal diet (intake of vitamin D3, 5 IU/day/100 g of body weight). Three of 20 marmosets were found by X-ray examination to have osteomalacic changes in their bones despite the high daily intake of vitamin D3, whereas none of the 5 rhesus monkeys showed any signs of osteomalacia. Osteomalacic marmosets had distinct increases in osteoid surface, relative osteoid volume, and active osteoclastic bone resorption, whereas non-osteomalacic marmosets had no increase in osteoid tissues in their bones. None of the marmosets, either osteomalacic or non-osteomalacic, was hypercalcemic despite the extremely high circulating levels of 1 alpha,25(OH)2D3. However, the serum 25-hydroxyvitamin D3 (25OHD3) and 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) levels were significantly lower in the osteomalacic than in the non-osteomalacic marmosets. These results suggest that the marmoset is likely to exhibit osteomalacic bone changes despite the high daily intake of vitamin D3. These changes resemble those in vitamin D-dependent rickets, type II.

24,25-Dihydroxyvitamin D 3↗
PubMed1986

Comparison of the mechanisms of bone resorption induced by 1 alpha,25-dihydroxyvitamin D3 and lipopolysaccharides.

The mechanisms of increase in bone resorption induced by 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] and bacterial lipopolysaccharides (LPS) were compared in an in vitro dead bone assay and a living bone assay. 1 alpha,25(OH)2D3 at concentrations of 0.05-5 ng/ml dose-dependently enhanced the ability of alveolar macrophages to release 45Ca from prelabeled dead bone particles (dead bone assay). In addition, the vitamin promoted fusion of the macrophages to form multinucleated cells and also enhanced glucose consumption, a marker of activation of macrophages. LPS at 0.05-5 micrograms/ml similarly enhanced the release of 45Ca from the dead bone particles and glucose consumption by alveolar macrophages, but it did not induce fusion of the cells at any concentration. Both 1 alpha,25(OH)2D3 and LPS dose-dependently stimulated the release of 45Ca from fetal mouse calvaria prelabeled with 45Ca (living bone assay). Compared to control bone, there were several times as many osteoclasts per given length of trabecular bone surface in calvaria treated for 5 days with either 5 ng/ml of 1 alpha,25(OH)2D3 or 5 micrograms/ml of LPS. Indomethacin (10(-5) M) completely inhibited the LPD-induced increase of osteoclasts, but not the 1 alpha,25(OH)2D3-induced increase. These results suggest that 1 alpha,25(OH)2D3 and LPS similarly stimulate bone resorption by activating macrophages as well as by promoting fusion of precursor cells to form multinucleated cells. 1 alpha,25(OH)2D3 induced formation of multinucleated cells with bone-resorbing activity directly, whereas LPS appeared to induce multinucleated cells through prostaglandin synthesis by some other types of cells present in living bone tissues.

Animals↗
PubMed1986

In vitro early changes in intercellular junctions by treatment with a chemical carcinogen.

To examine early intercellular junction changes caused by treatment with 9,10-dimethyl-1,2-benzanthracene (DMBA), rat lingual epithelium was cultivated in isolation and observed by electrophysiological, freeze-fracture and whole-mount electron microscopy. Electrophysiological measurements showed a transient decrease in membrane potential of -10.2 mV 6 h after the treatment. It returned to almost the same level as that of the control group 1 day later. Six hours after treatment, input resistance decreased rapidly to 5.3 M omega but increased to 18.0 M omega 12 h after treatment. Transient reduction of input resistance and membrane potential occurred prior to the decrease in the coupling ratio 6 h after treatment with DMBA. In freeze-fracture replicas, the number of gap junctions decreased by approximately 45% of the control value 6 h after treatment with DMBA. At 12 h and thereafter, the number and area of gap junctions subsequently decreased by 60-80% of the control value. Alterations in the number and area of desmosomes were similar to those of the gap junctions. The formation of epithelial cytoskeletons, partially devoid of the 2-4 and 5-8 nm filaments was also observed. A decrease in the density of filament networks beneath the plasma membranes was especially apparent. Treatment with a carcinogen brought about morphological cellular changes as early as 6 h after treatment, and such early changes might trigger metabolic cellular abnormalities. Affected cells appear to move away from normal cells in a process of repeated destruction and revision of intercellular junctions, and cytoskeletons.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1986

[Histopathological studies of the osteophytes and ossification of the posterior longitudinal ligament (OPLL) in the cervical spine].

To obtain information on ossification around the vertebral body of the cervical spine, we carried out histopathological investigation on 30 autopsy cases. The results were as follows; Intervertebral discs were untouched, anterior osteophytes developed along the anterior longitudinal ligament and they corresponded to anterior spur in spondylosis deformans. Posterior osteophytes around the posterior edges of vertebral body resulted in intervertebral insufficiency, and corresponded to hypertrophic spur in osteochondrosis. Histopathological findings of hyperostotic anterior osteophytes were similar to anterior osteophytes, but in the former there were advanced osteophyte formations. In OPLL of the segmental type, intervertebral discs were degenerated, and ossified mass did not involve the posterior longitudinal ligament of the parts of discs. With regard to morphological appearance and the tendency of increasing ossification, OPLL of the continuous type was similar to hyperostotic anterior osteophytes, without involvement of intervertebral disc. OPLL of the distinctly continuous type was differentiated from that of the segmental type.

Adult↗
PubMed1985

Uptake of horseradish peroxidase by bone cells during endochondral bone development.

To investigate the mechanisms whereby bone cells absorb organic bone-matrix components during endochondral bone development, rat humeri were examined, employing horseradish peroxidase as a soluble protein tracer. Intravenously-injected peroxidase filled the osteoid layer and penetrated into the osteocyte lacunae and canaliculi, but did not enter the mineralized bone matrix. Whereas osteocytes rarely took up exogenous peroxidase, osteoblasts and osteoclasts actively endocytosed peroxidase in pinocytotic coated vesicles, tubular structures, and vacuoles. They also formed endocytotic vacuoles containing peroxidase in the Golgi area. The Golgi apparatus and dense bodies of these bone cells were, however, free of reaction products. Osteoclast ruffled borders were responsible for peroxidase absorption. In the osteoblast, osteocyte and osteoclast, endogenous peroxidatic reaction was detected only in mitochondria and not in other membrane-bounded vesicles and bodies. These results strongly suggest that both osteoblasts and osteoclasts participate in the resorption of bone-matrix organic components during bone remodelling.

Animals↗