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  • 1
    Electronic Resource
    Electronic Resource
    Lethal photosensitization of periodontal pathogens by a red-filtered Xenon lamp in vitro (2003)
    Oxford, UK : Munksgaard International Publishers
    Journal of periodontal research 38 (2003), S. 0 
    Details
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  The ability of Helium–Neon (He–Ne) laser irradiation of a photosensitizer to induce localized phototoxic effects that kill periodontal pathogens is well documented and is termed photodynamic therapy (PDT).Objectives:  We investigated the potential of a conventional light source (red-filtered Xenon lamp) to activate toluidine blue O (TBO) in vitro and determined in vitro model parameters that may be used in future in vivo trials.Materials and methods:  Porphyromonas gingivalis 381 was used as the primary test bacterium.Results:  Treatment with a 2.2 J/cm2 light dose and 50 µg/ml TBO concentration resulted in a bacterial kill of 2.43 ± 0.39 logs with the He–Ne laser control and 3.34 ± 0.24 logs with the lamp, a near 10-fold increase (p = 0.028). Increases in light intensity produced significantly higher killing (p = 0.012) that plateaued at 25 mW/cm2. There was a linear relationship between light dose and bacterial killing (r2 = 0.916); as light dose was increased bacterial survival decreased. No such relationship was found for the drug concentrations tested. Addition of serum or blood at 50% v/v to the P. gingivalis suspension prior to irradiation diminished killing from approximately 5 logs to 3 logs at 10 J/cm2. When serum was washed off, killing returned to 5 logs for all species tested except Bacteroides forsythus (3.92 ± 0.68 logs kill).Conclusions:  The data indicate that PDT utilizing a conventional light source is at least as effective as laser-induced treatment in vitro. Furthermore, PDT achieves significant bactericidal activity in the presence of serum and blood when used with the set parameters of 10 J/cm2, 100 mW/cm2 and 12.5 µg/ml TBO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0765.2003.00673.x
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  • 2
    Electronic Resource
    Electronic Resource
    Emdogain® regulation of cellular differentiation in wounded rat periodontium (2003)
    Oxford, UK : Munksgaard International Publishers
    Journal of periodontal research 38 (2003), S. 0 
    Details
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Emdogain® is an enamel matrix derivative that may promote periodontal regeneration by recapitulating critical events in tooth morphogenesis. We hypothesized that Emdogain® enhances periodontal regeneration by promoting the differentiation of cells required for the synthesis of periodontal ligament, bone and cementum. Cell differentiation was examined in rat periodontal window wounds in which there is no microbial biofilm or epithelial downgrowth, thereby simplifying the model system. Defects were filled with vehicle control or Emdogain® (3 mg/ml or 30 mg/ml). Rats were sacrificed at 7, 14 and 21 d after wounding. Specimens of periodontium were immunostained for osteopontin, bone sialoprotein, osteocalcin as markers of osteogenic differentiation and for α-smooth muscle actin, a myofibroblastic marker. Morphometry and 3H-proline radioautography were used for assessment of tissue homeostasis and matrix production. Rats treated with Emdogain® (only at 30 mg/ml) showed widening of the periodontal ligament at 7 d; by 14 and 21 d, periodontal ligament width was restored to normal values for all groups. Emdogain® exerted no effect on cementum thickness, bone volume, osteoid deposition rates, or extracellular staining for osteopontin, bone sialoprotein or osteocalcin. Further, the percentage of cells with intracellular staining for osteopontin, osteocalcin or bone sialoprotein was unaffected by Emdogain®. Staining for α-smooth muscle actin was abundant in the repopulating wound but was also unaffected by Emdogain®. In conclusion, Emdogain® does not apparently affect the expression of differentiation markers or bone matrix protein synthesis in the repopulation response of wounded rat molar periodontium. Therefore the effect of Emdogain® on wound healing in the periodontium may be independent of differentiation in the cell populations examined in this model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0765.2003.00003.x
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  • 3
    Electronic Resource
    Electronic Resource
    Replantation of permanent incisors in children using Emdogain® (2005)
    Oxford, UK : Munksgaard International Publishers
    Dental traumatology 21 (2005), S. 0 
    Details
    ISSN: 1600-0595
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract –  The aim of this study was to determine whether application of an enamel matrix protein derivative, Emdogain® (Biora AB Malmo, Sweden) to the root surface of avulsed permanent incisors would improve postreplantation outcomes in a pediatric population. Between June 1999 and May 2002, 25 avulsed permanent maxillary incisors (22 centrals and three laterals) were treated with Emdogain® and followed for up to 32 months, mean duration 20.6 months (range: 6.9–32.5 months). Mean patient age at the time of treatment was 12.0 years (range: 7.7–17.6 years) and mean extra-alveolar duration was 185 min (range: 100–300 min). At the end of their follow-up each of the replanted incisors demonstrated radiographic evidence of replacement root resorption and clinical evidence of ankylosis. None of the replanted teeth were affected by inflammatory root resorption and there was no evidence of infection. When compared with the control samples from Barrett and Kenny (Endod Dent Traumatol 1997;15:269–72.) and Andersson et al. (Endod Dent Traumatol 1989;5:38–47.) this sample treated with the Emdogain® protocol demonstrated significantly less root resorption than either of the control samples (anova, P 〈 0.0001). Although the Emdogain® protocol did not produce periodontal regeneration, it did eliminate inflammatory resorption and infection and led to significantly less root resorption compared with the two historical controls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-9657.2005.00316.x
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  • 4
    Electronic Resource
    Electronic Resource
    Expression of bone sialoprotein and osteopontin in breast cancer bone metastases (2000)
    Springer
    Clinical & experimental metastasis 18 (2000), S. 253-260 
    Details
    ISSN: 1573-7276
    Keywords: bone sialoprotein ; osteopontin ; breast cancer ; metastasis ; bone metastases ; immunohistochemistry ; in situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Bone sialoprotein (BSP) and osteopontin (OPN) are prominent, mineral-associated proteins in the extracellular matrix of bone that have been implicated in the metastatic activity of cancer cells. The expression of BSP, which is normally restricted to mineralizing tissues, has been observed in cancers with a high propensity for forming bone metastases. To investigate the relationship between BSP expression and the formation of bone metastases we have conducted an initial study of the expression of BSP in 10 intraductal breast carcinoma bone metastases using immunostaining and in situ hybridization, and compared the expression with OPN. The metastases were characterized by the infiltration of tumour cells into bone with extensive bone resorption evident. Moderate to strong staining for BSP was observed in all (100%) carcinomas, which also expressed BSP mRNA as determined by in situ hybridization. Variable staining for BSP was also observed in the mineralized bone and expression of BSP mRNA could be observed in osteoblastic cells on the bone surface and in some osteocytes at sites of bone remodelling. Contrary to a previous report, BSP expression could be demonstrated by PCR in three breast cancer cell lines, MCF-7, T47-D and MDA-MB-231. Moreover, in sub-cutaneous tumours formed by MDA-MB-231 breast cancer cells injected into athymic mice, higher immunostaining for BSP was seen in large ulcerating tumours in which mineral deposits were formed. In contrast to BSP, staining for OPN in bone metastases was generally restricted to the interface between tumor cells and bone surface of the carcinomas. While OPN staining was also observed in the cytoplasm of osteoclasts, which showed strong hybridization to a digoxygenin-labelled OPN cRNA probe, expression of OPN was not clearly detectable in the tumour cells. These studies provide the first demonstration of BSP expression by tumour cells in bone metastases and support the concept that BSP may have a role in targeting metastatic cells to bone. Expression of OPN in bone metastases appears to be related to increased bone resorptive activity by osteoclasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006754605901
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  • 5
    Electronic Resource
    Electronic Resource
    Osteogenic and osteoclastic cell interaction: development of a co-culture system (1998)
    Springer
    Cell & tissue research 294 (1998), S. 99-108 
    Details
    ISSN: 1432-0878
    Keywords: Key words Bone formation ; Mineral resorption ; Stromal cells ; Osteoblasts ; Osteoclasts ; Biomaterials ; Chicken (culture)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The processes involved in the regulation of bone cell metabolism are complex, including those implicated in bone cell coupling. This study was undertaken to develop a model that would permit real-time interaction between osteoclastic cells and osteoblasts in vitro. Osteogenic bone marrow stromal cells were isolated from 18-day-old embryonic chickens, while osteoclastic cells were isolated from laying White Leghorn hens on calcium-deficient diets. Osteoclastic cells (5×105) were seeded onto mineral thin films and suspended above osteogenic cells (1×104) already plated on the bottoms of tissue culture plate wells. The data showed that after 4 days of incubation there was up to a fivefold (P〈0.05) reduction in all measured parameters of osteogenesis (mineralization, alkaline phosphatase activity and type I collagen production) in osteogenic cultures grown in the presence of osteoclastic cells. Similarly, osteoclastic cell-induced mineral resorption was reduced up to threefold (P〈0.05). Co-culture effects on cellular responses could be manipulated by known antiresorptive agents (e.g., pamidronate) altering either the source or the age of osteoclastic cells. The results indicate that the co-culture model may be useful in the study of bone cell interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051160
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  • 6
    Electronic Resource
    Electronic Resource
    Osteogenic inhibition by rat periodontal ligament cells: modulation of bone morphogenic protein-7 activity in vivo (1998)
    Springer
    Cell & tissue research 294 (1998), S. 475-483 
    Details
    ISSN: 1432-0878
    Keywords: Key words Periodontal ligament ; α-Smooth muscle actin ; Osteopontin ; Bone sialoprotein ; Bone morphogenic protein ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Periodontal ligament width is precisely maintained throughout the lifetime of adult mammals but the biological mechanisms that inhibit ingrowth of bone into this soft connective tissue are unknown. As bone morphogenic proteins strongly stimulate osteogenesis and can induce ectopic bone formation in vivo, we tested the hypothesis that topical application of this powerful osteogenic agent will overwhelm the osteogenic inhibitory mechanisms of periodontal ligament cells and induce ankylosis. Wounds through the alveolar bone and periodontal ligament were created in 45 male Wistar rats. Defects were filled with either a collagen implant or collagen plus bone morphogenic protein (BMP-7), or were left unfilled (controls). Three animals per time period were killed on days 2, 5, 10, 21 and 60 after surgery for each wound type. Cellular proliferation and clonal growth in periodontal tissues were assessed by 3H-thymidine labeling 1 h before death, followed by radioautography. Cellular differentiation of soft and mineralizing connective tissue cell populations was determined by immunohistochemical staining of α-smooth muscle actin, osteopontin and bone sialoprotein. In regenerating periodontium, BMP-7 induced abundant bone formation by 21 days (2.5-fold greater than controls or collagen implant only; P〈0.001), but by day 60 the volume of the newly formed bone had returned to baseline levels and was similar for all groups. Independent of the type of treatment, periodontal ligament width was unchanged throughout the experimental period (P〉0.05). Animals treated with BMP-7 implants showed greatly increased cellular proliferation in the periodontal ligament adjacent to the wound site and in the regenerating alveolar bone at days 5 and 10 after wounding compared to the other treatment groups (P〈0.005). Animals in the BMP-7 group exhibited similar spatial and temporal staining patterns for α-smooth muscle actin, osteopontin and bone sialoprotein as controls. Collectively, these data show that BMP-7 promoted the proliferation of precursor cells in the periodontal ligament but did not induce osteogenic differentiation in this compartment. Consequently a powerful osteogenic stimulus like BMP-7 cannot significantly perturb the mechanisms that regulate periodontal ligament width and maintain periodontal homeostasis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051199
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  • 7
    Electronic Resource
    Electronic Resource
    Site-specific regulation of osteogenesis: Maintenance of discrete levels of phenotypic expression in vitro (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 223 (1989), S. 27-34 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Intrinsic differences in bone formation rate, cell numbers, and the percentages of cells expressing alkaline phosphatase activity were studied in explants of chick calvaria periosteum cultured for 4 days and 6 days. Proliferation, differentiation, and bone production were examined in radioautographs of plastic sections and by using whole-culture biochemical assays of protein and alkaline phosphatase. Ectocranial explants at both 4 days and 6 days exhibited more alkaline phosphatase-positive cells and significantly more bone formation than endocranial cultures. There were no detectable differences in cell numbers or 3H-thymidine labeling indices. The volume of bone synthesized per osteoblast was significantly higher in the ectocranial group. Examination of bone stripped of periostea and then cultured for 4 days revealed that large areas of bone were covered by osteoblasts, indicating that the periosteal explant cultures were composed almost exclusively of osteoprogenitor cells and fibroblasts. The data suggest that the level of expression of predetermined osteogenic phenotypes can be maintained in vitro for 6 days following explantation and that variations in the rate of osteogenesis are programmed into progenitor cells prior to their differentiation into osteoblasts.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092230105
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  • 8
    Electronic Resource
    Electronic Resource
    Probing glucocorticoid-dependent osteogenesis in rat and chick cells in vitro by specific blockade of osteoblastic differentiation with progesterone and RU38486 (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 242 (1995), S. 200-210 
    Details
    ISSN: 0003-276X
    Keywords: Osteogenesis in vitro ; Sex-steroids ; Glucocorticoid ; Differentiation ; Rat ; Chicken ; Bone ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Glucocorticoids and sex-steroids can modulate osteogenesis in vivo and in vitro. Although the effects of glucocorticoids on bone cells in vitro have been described in detail, the role of sex-steroids is not as well defined. We examined whether sex-steroids influence bone metabolism indirectly by regulating glucocorticoid effects on bone. Interactions of the sex-steroid progesterone or its analog RU38486 with the glucocorticoid dexamethasone (dex) were studied in functional assays of osteogenesis. Three osteoblastic models were evaluated:(1) the rat bone marrow stromal cell (RBMC) nodule system; (2) the chick periosteal osteogenesis (CPO) model; and (3) ROS 17/2.8 cells. RU38486, progesterone, and unlabelled dex competitively inhibited 3H-dex uptake by ROS 17/2.8 cells as well as its (3H-dex) binding to cytosol preps.Both RU38486 and progesterone inhibited dex-induced increases in alkaline phosphatase in CPO cultures, in RBMC cultures, and in ROS 17/2.8 cells. Dex-induced decreases in cell proliferation in ROS 17/2.8 cells were reversed by RU38486 but dex-induced increases in proliferation in the CPO model were not affected. In CPO cultures, dex-induced increases in collagen synthesis were inhibited completely by RU38486 and progesterone, Dex-dependent nodule formation in the RBMC was blocked by RU38486. Both RU38486 and dex mediated reduction of calcium uptake in the CPO model but did not affect mineralized tissue area.The data indicate that RU38486 and progesterone competitively inhibit dex-mediated stimulation of osteogenesis in vitro; this inhibition is exerted on early but not late stage differentiation events of osteoprogenitor cells. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092420209
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