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Biomedical subjects

A Shimazu

Publications and source records attributed to A Shimazu.

At least 19 recordsLinked to original sources
PubMed2006

The effect of intrathecal fentanyl added to hyperbaric bupivacaine on maternal respiratory function during Cesarean section.

BACKGROUND: Subarachnoid blockade with local anesthetics induces respiratory depression. Although the addition of fentanyl to bupivacaine has become popular in subarachnoid blockade for Cesarean section, there is no information on the effect of intrathecal fentanyl on maternal spirometric respiratory function in parturients undergoing Cesarean section. METHODS: We tested the effect of the addition of intrathecal fentanyl to hyperbaric bupivacaine on maternal spirometric performance in 40 consenting parturients undergoing Cesarean section. The parturients were randomized into two groups: those receiving 2.0 ml of hyperbaric bupivacaine 0.5% and 0.4 ml of saline intrathecally and those receiving 2.0 ml of hyperbaric bupivacaine and 0.4 ml of fentanyl (20 microg) intrathecally. We performed spirometry on arriving at the operation room and 15 min after subarachnoid blockade. RESULTS: Subarachnoid blockade with bupivacaine significantly decreased the peak expiratory flow rate, but did not induce significant changes in vital capacity and forced vital capacity. The addition of intrathecal fentanyl to bupivacaine improved the quality of subarachnoid blockade, but did not lead to a deterioration in respiratory function compared with intrathecal bupivacaine alone. CONCLUSIONS: The addition of intrathecal fentanyl to hyperbaric bupivacaine did not lead to a deterioration in maternal spirometric respiratory function in parturients undergoing Cesarean section.

Adult↗
PubMed2004

Characterization of CO3Ap-collagen sponges using X-ray high-resolution microtomography.

For reconstruction and regeneration of hard tissues, scaffold biomaterials with large size pores and high porosity are important, in addition to their roles as supporting frames. To develop a new biodegradable scaffold biomaterial, CO3Ap, which has crystallinity and a chemical composition similar to bone, was synthesized at pH 7.4 and 60 degrees C. Then, the CO3Ap was mixed with a neutralized collagen gel and the CO3Ap-collagen mixtures with different kinds of CO3Ap contents and porosity were lyophilized into sponges. Scanning electron micrography (SEM) observation of CO3Ap-collagen sponges showed favorable pores for cell invasion. Approximately 50-300 microm size pores appeared to continue through the bulk. Higher magnification of the sponge showed a better adhesion between CO3Ap crystals and collagen. X-ray high-resolution microtomography revealed a clear image of the 3D structure of the sponges. The porosity of 0, 70 and 90%(w/w) CO3Ap-collagen sponges was 79.2 +/- 2.8%, 72.6 +/- 2.4% and 48.9 +/- 6.1%, respectively. The 70%(w/w) CO3Ap-collagen sponge appeared to be the most favorable biomaterial from the viewpoint of natural bone properties. Mouse osteoblast MC3T3-E1 cells were cultured in alphaMEM with 10% FCS for 2 weeks. Hematoxylin-eosin staining confirmed osteoblast cells invaded well into the CO3Ap-collagen sponge. These sponges are expected to be used as hard tissue scaffold biomaterials for therapeutic uses.

3T3 Cells↗
PubMed2003

Action of FGMgCO3Ap-collagen composite in promoting bone formation.

To improve the biological properties of materials as bone substitutes, functionally graded CO3 apatite crystals containing magnesium, FGMgCO3Ap, were synthesized to be mixed with atelocollagen and made into a composite pellet. A radio-labeled cell adhesion experiment showed that the degree of adherence of mouse MC3T3E1 osteoblast-like cells to the FGMgCO3Ap-collagen composite was better than to CO3Ap-collagen and much better than to the Ti plate. When the composites were implanted beneath the periosteum cranii of rats, the FGMgCO3Ap-collagen composite was metabolized faster than the CO3Ap-collagen composite and better formation of new bone and osteoblast arrangement at the interface between the composite and the periosteum cranii was observed. When the composites were implanted into the femur of rabbits, clear bone formation with a higher degree of bone density was observed for the FGMgCO3Ap-collagen composite. These results suggest that the Mg2+ ions taken into the apatite crystals may contribute to the acceleration of osteoblast adhesion to apatites and promote bone formation, cross-talking with osteoblasts at the molecular level.

3-Hydroxysteroid Dehydrogenases↗
PubMed2002

Synthesis of functionally graded MgCO3 apatite accelerating osteoblast adhesion.

As a means of improving the biological properties of materials for use as bone substitutes, functionally graded carbonate apatite containing Mg, FGMgCO3Ap, was synthesized at 60 degrees C and pH 7.4 using a gradient magnesium supply system. X-ray diffraction analysis of FGMgCO3Ap showed a poorly crystallized apatitic pattern, similar to that of human bone. ESCA analysis clearly showed the negative gradient distribution in Mg1s intensity (atomic concentration) of magnesium from the crystal surface toward the inner core. When the FGMgCO3Ap crystals were mixed with collagen, the resulting FGMgCO3Ap-collagen composite, irradiated with UV light for 4 h, retained their features in the saline solution. After washing away the nonadhesive cells, a cell adhesion assay showed that the optical density of the FGMgCO3Ap-collagen composite was higher than that of the CO3Ap-collagen composite. SEM observation showed that the osteoblast-like cells adhered well to the surface of the FGMgCO3Ap-collagen composite. Staining with hematoxylin-eosin and alizarin red confirmed the existence of a great many more cells and a thicker extracellular matrix layer on the FGMgCO3Ap-collagen composite than on the CO3Ap-collagen composite. This result demonstrated the acceleration effect of magnesium ions on osteoblast adhesion on the FGMgCO3Ap-collagen composite.

Animals↗
PubMed2001

Retention of multilineage differentiation potential of mesenchymal cells during proliferation in response to FGF.

Mesenchymal stem cells (MSC) that can differentiate to various connective tissue cells may be useful for autologous cell transplantation to defects of bone, cartilage, and tendon, if MSC can be expanded in vitro. However, a short life span of MSC and a reduction in their differentiation potential in culture have limited their clinical application. The purpose of this study is to identify a growth factor(s) involved in self-renewal of MSC and the maintenance of their multilineage differentiation potential. Fibroblast growth factor-2 (FGF-2) markedly increased the growth rate and the life span of rabbit, canine, and human bone marrow MSC in monolayer cultures. This effect of FGF-2 was more prominent in low-density cultures than in high-density cultures. In addition, all MSC expanded in vitro with FGF-2, but not without FGF-2, differentiated to chondrocytes in pellet cultures. The FGF+ MSC also retained the osteogenic and adipogenic potential throughout many mitotic divisions. These findings suggest that FGFs play a crucial role in self-renewal of MSC.

Animals↗
PubMed1999

Analysis of oestrogen receptor mRNA by reverse transcriptase-polymerase chain reaction in human periodontal ligament cells.

Periodontal ligament (PDL) cells have osteoblast-like features and are capable of differentiating into osteogenic cells. As human osteoblasts express oestrogen receptor mRNA, it is possible that PDL cells do so also, but findings have been conflicting. To determine whether they do express oestrogen receptor mRNA, the reverse transcriptase-polymerase chain reaction was performed with two different primers. Cells were obtained from a healthy periodontal ligament of premolar extracted for orthodontic reasons. The human breast adenocarcinoma cell-line MCF7 was used as a positive control. Expression of oestrogen receptor mRNA was detected in PDL cells with one of the primers but with less intensity than in MCF7 cells. Southern hybridization confirmed these results. These findings suggest that PDL cells express oestrogen receptor mRNA at low levels.

Adenocarcinoma↗
PubMed1999

Estradiol enhances the production of mineralized nodules by human periodontal ligament cells.

A primary objective in the treatment of periodontal disease is the regeneration of the mineralized and soft connective tissue. PDL cells produce mineralized nodules in vitro which is one of the important functions of PDL cells for regenerative therapy. The purpose of this study was to investigate the effects of estradiol on mineralized nodule formation by human PDL cells. PDL cells were obtained from healthy donors and maintained in DMEM with 10% fetal bovine serum. Serum-free medium was used when the effects of estradiol were tested. ALP activity in the supernatant of cells disrupted by sonication was analyzed spectrophotometrically. The formation of mineralized nodules was assessed by staining the PDL cells with alizarine red and counting the number of nodules. at Estradiol 20 ng/ml significantly enhanced the ALP activity and mineralized nodule formation compared to the control. These results suggested that estrogen status may modify the regenerative activity of periodontal tissue.

Adolescent↗
PubMed1999

Expression of syndecan-2, -4, and fibroblast growth factor receptor type 1 in human periodontal ligament fibroblasts and down-regulation of these membrane proteins during maturation in culture.

Syndecans are transmembrane heparan sulfate proteoglycans. They are known to interact with basic fibroblast growth factor (bFGF), and it has been suggested that they play important roles in the growth, morphology, and migration of a variety of cell types. We examined the expression of syndecans and fibroblast growth factor receptor type 1 (FGFR1) in periodontal ligament (PDL) cells, because these membrane proteins may play roles in the control of growth and differentiation during regeneration of PDL. Reverse-transcription/polymerase chain-reaction (RT-PCR) showed that PDL cells expressed syndecan-2 and -4 mRNAs. This was confirmed by sequence analysis of the PCR products. When PDL cells were maintained for 25 days, alkaline phosphatase (ALPase) activity gradually increased and reached a maximal level on day 20. Northern blotting analysis showed that PDL cells expressed 2.3-kb syndecan-2, 2.6-kb syndecan-4, and 2.8-kb FGFR1 mRNAs throughout the entire culture period, whereas no syndecan-1 mRNA was detectable by this method. Maximal levels of syndecan-2, -4, and FGFR1 mRNAs were observed on day 5. However, their levels were markedly decreased on days 20 and 25. Accordingly, the inhibitory effect of bFGF on ALPase activity was less on day 20 than on day 5. When PDL cells were pre-treated with heparitinase, a mitogenic response of PDL cells to bFGF was decreased. These observations indicate that PDL cells express syndecan-2, -4, and FGFR1 mRNAs, and that those levels are changed with the increase in ALPase activity in culture. The reductions in syndecan-2, -4, and FGFR1 levels may be involved in the control of growth and differentiation of PDL cells during development and regeneration.

Alkaline Phosphatase↗
PubMed1998

The effects of oestrogen on osteocalcin production by human periodontal ligament cells.

The purpose was to investigate the effects of oestradiol on the function of periodontal ligament (PDL) cells by measuring the production of osteocalcin in vitro. Cells were obtained from the healthy periodontal ligament of teeth extracted from two males and two females for orthodontic reasons. Serum-free medium was used when testing the effects of oestradiol on PDL cells. The amount of osteocalcin in the culture medium was analysed by two-step sandwich enzyme immunoassay in the presence or absence of oestradiol. It was shown that oestradiol enhanced the production of osteocalcin by PDL cells in a time- and dose-dependent manner. PDL cells obtained from both male and female donors were affected by oestradiol. It thus appears that oestradiol is one of the factors important for PDL cells to express their function.

Adult↗
PubMed1998

[The developmental process of employee maladjustment in work place].

A causal model of job stressors and stress reactions was examined to clarify the developmental process of employee maladjustment in work place. Two thousand seven hundred twenty-eight (2728) employees of a research institute in the automobile industry completed Job Stress Scale (JSS), which measured job stressors, stress reactions, coping strategies, and social support. Three hundred ninety-two (392) employees with high stress reaction scores were interviewed to obtain information to construct a theoretical model. Then, the model was evaluated with covariance structure analysis. Results showed that the quantitative job stressors had only an indirect effect, mediated by fatigue and irritability, on mental instability, whereas qualitative ones had both direct and indirect effects. The findings suggest that the developmental processes of employee maladjustment in work place differ depending on the kind of job stressors they experience.

Adaptation, Psychological↗
PubMed1997

Optimal configuration of pyrene excimer induced by the excimer-forming two-probe nucleic acid hybridization method.

Excimer-forming two-probe nucleic acid hybridization (ETPH) method with pyrene as a fluorophore enables homogeneous hybridization assays. We examined the effect of linker length between a pyrene residue and a terminal sugar moiety on Tm of hybrids in the presence of 20% dimethylformamide (DMF). The results including those of CD measurements indicated no interaction of pyrene residues with the duplex formed between a target 32-mer and a pyrenemethyliodoacetamide-introduced 16-mer probe (PMIA-P5)/a pyrenebutanoic acid-introduced 16-mer probe (PBuA-P3), which is the best pair of probes for intense excimer emission. This was also supported by a computer-assisted molecular modeling using Insight II and Discover software.

DNA↗
PubMed1996

Syndecan-3 and the control of chondrocyte proliferation during endochondral ossification.

During endochondral ossification, chondrocytes progress through several stages of maturation before they are replaced by bone cells. Chondrocyte proliferation, the first step in this complex multistage process, is strictly controlled both spatially and temporally but its underlying mechanisms of regulation remain unclear. In this study we asked whether chondrocytes produce syndecan-3, a cell surface receptor for growth factors such as fibroblast growth factor 2 (FGF-2), and whether syndecan-3 may play a role in proliferation during chondrocyte maturation. We found that proliferating immature cartilage from chick embryo tibia and sternum contained significant amounts of syndecan-3 mRNA, whereas mature hypertrophic cartilage contained markedly lower transcript levels. Immunohistochemical analyses on sections of Day 18 chick embryo tibia revealed that syndecan-3 was spatially restricted and indeed detectable only in immature proliferating chondrocytes in the top zone of growth plate. These syndecan-3-rich proliferating chondrocytes lay beneath developing articular chondrocytes rich in their typical matrix protein tenascin-C, resulting in a striking boundary between these two populations of chondrocytes. Immature proliferating chondrocyte populations reared in growth-promoting culture conditions displayed strong continuous syndecan-3 gene expression; upon induction of maturation by vitamin C treatment, syndecan-3 gene expression was markedly down-regulated. Treatment with FGF-2 for 24 h stimulated both syndecan-3 gene expression and chondrocyte proliferation; this growth stimulation was counteracted by cotreatment with heparinase I or III. The results of the study indicate that syndecan-3 participates in the maturation of chondrocytes during endochondral ossification and represents a regulator of the proliferative phase of this multistage process.

Animals↗
PubMed1996

Expression of syndecan-3 and tenascin-C: possible involvement in periosteum development.

The development of cartilaginous elements of long bone during embryogenesis and postnatal bone repair processes is a complex process that involves skeletal cells and surrounding mesenchymal periosteal cells. Relatively little is known of the mechanisms underlying these processes. Previous studies from this and other laboratories have suggested that the extracellular matrix protein tenascin-C is involved in skeletogenesis. Using in situ hybridization and immunofluorescence, we extended those studies by comparing the expression of tenascin-C with that of syndecan-3, which belongs to a family of cell surface receptors with which tenascins are known to interact. We found that syndecan-3 transcripts at first were very abundant in the presumptive periosteum surrounding the diaphysis of early chondrocytic skeletal elements in chick limb. As the elements developed further, syndecan-3 gene expression decreased in the diaphyseal periosteum, whereas it became stronger around the early epiphysis and within the forming articular cells. However, as the diaphyseal periosteum initiated osteogenesis and gave rise to the intramembranous bone collar, syndecan-3 gene expression increased again. At early stages of skeletogenesis: the tenascin-C gene exhibited patterns of expression that were similar to and temporally followed, those of the syndecan-3 gene. At later stages, however, tenascin-C gene expression was markedly reduced during intramembranous osteogenesis around the diaphysis. In addition, although syndecan-3 gene expression was low in osteoblasts and osteocytes located deep into trabecular bone, tenascin-C gene expression remained strong. Thus, tenascin-C and syndecan-3 display distinct temporal and spatial patterns of expression in periosteum and during the development of long bone. Given their multidomain structure and specific patterns of expression, these macromolecules may regulate site-specific skeletal processes, including interactions between developing periosteum and chondrocytes and delineation of the early cartilaginous skeletal elements.

Animals↗
PubMed1996

The role of physicochemical properties of biomaterials and bacterial cell adhesion in vitro.

This study was undertaken to investigate the physicochemical aspects of the interaction between the surface of biomaterials and bacterial cell membranes in vitro, aimed at studying the mechanisms of bacterial adhesion to biomaterials. Correlations were made between the number of adherent bacterial cells (S. aureus) and each of the calculated components of surface free energy (i.e., dispersion, polarity and hydrogen bond) of biomaterials. The effect of antibodies to cell-adhesion molecules on bacterial adhesion was also studied using monoclonal antibodies to vitronectin receptor, fibronectin receptor and CD44. This study indicates the polarity component of surface free energy plays a dominant role in the process of bacterial adhesion at least in vitro. The number of cells adherent to materials decreased to 44-73% of the control value in the presence of antibodies tested, showing that cell adhesion molecules affect adherence to biomaterials. Moreover, the results suggested that bacterial adhesion was prevented by specific blockade of cell adhesion molecule receptors.

Antibodies, Monoclonal↗
PubMed1995

Syndecan-3, tenascin-C, and the development of cartilaginous skeletal elements and joints in chick limbs.

The mechanisms by which the early limb cell condensations and interzone mesenchyme give rise to skeletal elements and joints are poorly understood. Previous work from this laboratory has shown that the extracellular matrix protein tenascin-C is associated with articular cartilage and joint tissue development; others have shown that tenascin-C may exert its biological activities via interactions with cell surface receptors, such as syndecans. To further analyze the roles of tenascin-C and its putative receptors in skeletal development, we carried out a detailed in situ hybridization analysis of tenascin-C and syndecan-3 gene expression during development of chick limb skeletal elements and joints. We found that as the early mesenchymal condensations chondrify around day 5 (E5) of development, they become surrounded by a thick syndecan-3 rich perichondrium while tenascin-C transcripts are much fewer and restricted to diaphyseal perichondrium and developing interzones. Similar patterns were observed as distal carpal and digit condensations formed in older embryos. As the cartilaginous long bone models elongated proximo-distally and joint formation proceeded with age, we observed that syndecan-3 transcripts decrease significantly along the diaphysis and remain very abundant along the metaphysis and in the epiphyseal articular cap and interzone. Conversely, tenascin-C RNAs remain abundant along the diaphysis and begin to increase at the epiphysis and in interzone-derived tissues, such as menisci and joint capsule. By E10, the skeletal elements have well-defined morphologies, endochondral ossification has initiated in their diaphysis, and diaphyseal perichondrium has become periosteum. These developmental changes were accompanied by equally marked changes in gene expression; these included a marked increase in tenascin-C gene expression in articular cap, fragmentation of tenascin-C gene expression along the periosteum, reinitiation of syndecan-3 gene expression in periosteum, and differential gene expression in osteoprogenitor cells. The sheer complexity of the gene expression patterns documented in this study attests to the complexity of processes that bring about normal skelatogenesis. Clearly, tenascin-C and syndecan-3 appear to be closely associated with several of these processes, particularly in establishing tissue boundaries (perichondrium and periosteum) between condensations and surrounding mesenchymal cells, in regulating perichondral cell differentiation and incorporation into the growing skeletal elements, and in the genesis of epiphyseal chondrocytes and associated joint tissues.

Animals↗
PubMed1995

Regulation of chondrocyte maturation by fibroblast growth factor-2 and parathyroid hormone.

Fibroblast growth factor-2 and parathyroid hormone are strong modulators of the maturation process of chondrocytes during endochondral ossification. To clarify whether and how these agents may exert stage-specific effects during this process, we analyzed the responsiveness and phenotypic consequences of treatment with fibroblast growth factor-2 or parathyroid hormone on chondrocytes at different stages of maturation. Populations of immature lower sternal, maturing upper sternal, and hypertrophic tibial growth plate chondrocytes were isolated from day 18-20 chick embryos and were allowed to resume the maturation process by growth in standard monolayer cultures. Treatment of immature lower sternal cultures with as little as 0.1 ng/ml of fibroblast growth factor-2 or 10(-10) M parathyroid hormone prevented both the emergence of mature type-X collagen-synthesizing chondrocytes and the ensuing enlargement of cells that occurred in control (untreated) cultures. Similarly, the treatment of cultured early maturing upper sternal cells with these factors severely reduced the synthesis of type-X collagen and alkaline phosphatase activity and the levels of their respective mRNAs. In sharp contrast, when the cultured upper sternal cells were allowed to grow and mature further before treatment, the responsiveness to fibroblast growth factor-2 was markedly reduced and the responsiveness to parathyroid hormone remained strong and largely unchanged. Cultures of hypertrophic tibial growth plate cells displayed a similar reduced sensitivity to fibroblast growth factor-2, as also indicated by the lack of mitogenic effects, and strong sensitivity to parathyroid hormone. The phenotypic changes induced by treatment with either of these factors were fully reversible when cultures that had been treated were placed in control medium. The results demonstrate that fibroblast growth factor-2 and parathyroid hormone are equally potent in affecting the early stages of maturation but exert differential effects as the cells progress along the maturation pathway. The factors appear to be part of sequentially acting mechanisms to ensure normal progression of chondrocyte maturation during endochondral ossification.

Alkaline Phosphatase↗
PubMed1995

Effects of hyaluronic acid on the release of cartilage matrix proteoglycan and fibronectin from the cell matrix layer of chondrocyte cultures: interactions between hyaluronic acid and chondroitin sulfate glycosaminoglycan.

Hyaluronic acid (HA) of large sizes suppressed the release of cartilage matrix proteoglycan, fibronectin, and other macromolecules from the cell matrix layer of chondrocyte cultures, perhaps because HA of large sizes formed a viscous barrier in the matrix by its interactions with other extracellular matrix macromolecules. To test this possibility, we determined the viscosity of solutions containing HA of various sizes in the presence of proteoglycan monomer or chondroitin sulfate glycosaminoglycan (GAG). Not only the monomer but also chondroitin sulfate increased the viscosity of HA solutions, depending on the size of HA. These findings suggest that HA of large sizes increases the viscosity near the surface of articular cartilage by sugar-sugar and by sugar-protein interactions and that the increase of viscosity is involved in the protective action of HA on arthritic cartilage.

Animals↗